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IBM PCjr

The IBM PCjr, released in 1984, is an interesting machine on several levels. First off it was a major failure for IBM who at the time was THE NAME in computers. Second, it was an “IBM PC compatible” from IBM that wasn’t even all that PC compatible. Lastly, despite being a failure for IBM, if it never existed, we probably would not have had one of the most beloved and successful computer lines of the 1980s and beyond, the Tandy 1000, which were essentially clones of the PCjr.

The PCjr was IBM’s attempt to bring their successful line of more business-oriented computers like the 5150 into the home. It was cheaper than the 5150 while at the same time having enhanced graphics and sound in order to make it more useful for things like games which would be more important to home users.

The PCjr supports 160 × 200 at 16 colors 320 × 200 at 16 colors and 640 × 200 at 4 colors. If this seems familiar that’s because the Tandy 1000 was a clone of the PCjr and supported the same enhanced video and 3-channel sound capabilities. Unfortunately, the machines aren’t fully compatible with one another so many games meant for the Tandy 1000 that use 16-color modes will either not work or will have graphical issues when run on the PCjr.

The PCjr is quite a small computer and quite a bit smaller and lighter than its IBM 5150 big brother. With this smaller size comes much less expandability and an all-plastic case. Most of the left of the case is taken up by some slots for airflow. next to these is a small black circle. This is actually an infrared sensor for the cordless keyboard (we will get to that). on the right side of the case, we have one 5 1/4 bay for the 360k 5 1/4 floppy drive, and below that we have two cartridge slots. Supposedly the PCjr can be made to work with 720K drives but I’ve never attempted it or seen it done.

The cartridge slots were part of the idea of making the computer more game-oriented as small games could be placed on a cart and then easily loaded onto the system for play. The idea didn’t really catch on though and very few cartridges were made for the PCjr with only about thirteen being released with a few of those being applications like Lotus 123 and Cart Basic.

The PCjr gets really strange when we turn it around and take a look at the rear of the machine.

IBM had the great idea with the PCjr to make more or less every connection on the rear proprietary. I suppose the thinking was with all the connectors being a mostly similar type it would simplify the ports and confuse users less. In the end, it just makes the PCjr more of a pain to connect peripherals like monitors to. As far as I know, no other computer uses these connector types. Thankfully there are adaptors available to make connecting non-IBM PCjr peripherals possible.

Starting from the left the the ports are as follows

  • J = Joystick ports (there are two of these)
  • L = Undocumented “spare” connector
  • K = Keyboard port if you decide to connect your keyboard via a cable (you should)
  • LP = Light Pen port
  • T = “Television” port for an external RF modulator
  • V = RCA style color composite port (not proprietary)
  • M = Optional modem card
  • D = “Display” port for connecting to the official TTL video 4863 IBM PCjr color monitor
  • S = Serial port
  • C = Cassette port
  • P = “Power” This is where you connect the external PCjr power supply
  • A = “Audio” which is a standard RCA-style audio output for the enhanced PCjr 3-channel sound

Before we take a look inside the PCjr let’s take a look at a few peripherals and the monitor.

The 14-inch IBM 4863 TTL monitor is the official monitor for the PCjr. It has a standard three-prong power connector attached to the case as well as a special connector for attaching to the proprietary display port on the PCjr. Unfortunately, this meant the monitor could only ever be connected to the PCjr. Fortunately, unofficial adaptors have been made for the 4863 that allow them to connect to other computers and cards that use the standard 9-pin digital TTL connector.

This picture does not do the excellent image displayed justice.

The monitor has a built-in speaker and also has possibly the nicest image I have ever seen from a CGA monitor. Perhaps my example simply has extremely low hours and I got lucky but I can’t stress enough how crisp and sharp the image I get from this monitor is.

Pretty standard joystick. Nothing really special but I can’t complain.

Finally, we come to the keyboard. As I mentioned earlier the keyboard is wireless and with a few AA batteries inserted uses a pair of infrared sensors to communicate with the PCjr.

In short, This keyboard is terrible. The wireless “feature” if you’d like to call it that, is unreliable at best and can easily be interfered with simply by lights in your room. Thankfully IBM had the sense to include a port to connect your keyboard via a wired connection and trust me, it is desired. The wired adaptors use a phone-style jack and even new old stock adaptors are still pretty easy to find. Unfortunately, the initial chicklet-style keyboard itself is pretty terrible and feels pretty bad to use. It’s so bad some people even blame this keyboard on the market failure of the PCjr.

The good news is IBM did release an improved revision of the PCjr keyboard featuring actual keys and a much better feel. If you can find one I strongly suggest using this over the original chicklet-style keyboard.

Before opening the PCjr I should mention the sidecarts. The primary way in which to expand the PCjr was via a connector located on the side of the PCjr, much like the side connector on the Amiga 500. Any number of sidecarts could be attached and daisy chained thus adding things like standard parallel ports and even memory expansion cards. After about two sidecarts though you would need to attach a special power sidecart which required its own power supply in order to power more cards. It’s pretty easy and convenient when you’re only adding one or two cards but anymore and it starts to be a bit ridiculous.

My only attached sidecart is a memory expansion card. Officially these only came in 128K sizes but mine has been modified to add 512K giving me a total of 640K of memory. Third parties have even made modern sidecarts for the PCjr that add real-time clocks as well as hard drives.

Here is the PCjr with the top of the case taken off. Although there are card slots on the motherboard they are very function specific and as far as I know no one has made any third-party cards for these slots besides direct replacement.

The card all the way to the right is the floppy controller card.

The card located in the center is in the slots specifically for memory expansion. Originally the PCjr shipped with 64K of memory on the board but IBM fairly quickly doubled that and shipped 128K PCjrs with a 64K memory expansion card installed.

I would suspect third-party modders could produce 512K internal cards though I have never seen anything except the 64K cards available.

Lastly, we have the power supply card inserted in the special power slot. Besides these longer cards, I have seen PCjrs with shorter cards. I have been told the longer power cards supply more wattage but I can’t confirm that. As a side note, you can also find several modern replacements for this card which, If you’re a PCjr fan may be a wise upgrade.

There isn’t a whole lot I’m experienced enough to point out going on inside the PCjr though there are a lot of chips. The Jr does have 64K of memory soldered onto the motherboard though without reading the chips I’m not sure where this is. I would suspect the cluster of “like” chips in the lower left side of the board is the RAM in question. In theory with memory expansion sidecarts the memory should be able to be brought up to a maximum of at least 720K. There is also no socket to add a math co-processor to the Jr though this would be expected as such a luxury would increase the cost and find little use in a computer more focused on the home and less on number crunching business or workstation tasks. The board also lacks a built-in DMA controller.

I would also like to once more bring up the enhanced video and sound capabilities of the PCjr which are also present in the Tandy 1000 line of home computers. Unfortunately due to how certain things are implemented differently on the PCjr and Tandy 1000 many games that take advantage of the 3-channel sound or 16-color video on the Tandy 1000 will not work or will display incorrectly on the PCjr. There is a cheap modification that is available that will make your PCjr much more compatible with Tandy 16-color mode.

The mod chip itself is only about $10 but it does require desoldering a chip from the motherboard so depending on your skill level this may be a deal breaker. You can find the required part here if you are interested in the modification.

1 ) CPU – Like the big brother 5150 the PCjr uses the 4.77MHz 8088 CPU. Most models I’ve come across have the CPU socketed which means it can be easily replaced with an NEC V20 for a small performance boost though later models had the CPU soldered to the board to cut costs.

In another case of “unfortunately” the video memory and system memory in the PCjr are shared in such a way that it slows down the 8088 CPU resulting in a CPU that runs at a speed more like 3.57MHz rather than 4.77MHz. Another source I read reported the CPU running 2.6 times slower than an 8088 in a 5150. Installing an NEC V20 may help offset this speed degradation. I have also read that this performance hit only affects programs running in the first 128K of memory and when running in any memory above 128K there is no performance hit.

2 ) Floppy controller and Modem slots – These small expansion slots, as far as I can tell, only support very specific cards with the slot closest to the right supporting the floppy drive controller card and the slot to the left of it supporting the optional modem card.

3 ) This is the special memory slot. As far as I can tell this slot only supports one card which is the official IBM 64K memory expansion card.

4 ) Power supply slot for connecting the internal power supply module.

Before wrapping things up I wanted to take a look at one final peripheral for the PCjr that I have in my possession.

This is the Quadram expansion unit and it adds more memory (I believe 384k) as well as a much-desired second floppy drive.

You will require a second power adaptor to power this attachment. I could not get mine to function and no matter what I attempted would get a memory error on boot and zero activity from the floppy drive. I’ve been told that breaks in the solder connection on the required sidecart are pretty common due to flexing and overtightening the attachment screws and I suspect mine is damaged beyond my ability to repair myself.

The IBM PCjr certainly is unique and a cool-looking little machine. I can definitely see its popularity with IBM collectors. I do have to say in no small terms that the IBM PCjr sucks…..a lot. Remember at the beginning of the article when I said IBM made an IBM PC compatible that wasn’t really PC compatible? I wasn’t lying. Due to how various things were implemented in the PCjr, compatibility with DOS and DOS games and applications is spotty. For instance, I wasn’t able to get my Jr to boot into my DOS 3.3 floppy and “see” the full 640K of memory until I ran a program called PCjrconfig and used it to patch and modify my DOS disk. Before running this program and essentially patching the disk my Jr could only utilize 128K under DOS which is very limiting as far as what games you can play. Even after patching DOS, I ran into several games that just would not play or would display incorrectly even in 4-color CGA mode. Games like Rogue wouldn’t even start and Paratrooper and Airborne Ranger gave various graphical glitches. Even running the benchmark program MIPs gave horrible visual glitches, though I’ve seen it run on a PCjr before so perhaps it requires a specific version. The newer game Planet X3 has a PCjr 16-color mode and it ran and looked fine although for whatever reason it had no sound.

Some games that did run correctly were Project Neptune in CGA mode, Thexder which ran fine with enhanced graphics and sound and Microsoft Flight Simulator which directly supports the IBM PCjr in its 16-color mode (and also has some kind of PCjr enhanced performance option as well).

Besides a novelty or if you’re a hardcore IBM collector, I really can’t think of a good reason to use a PCjr other than it’s an interesting conversation piece when it’s all hooked up. The Tandy 1000 does everything the PCjr does but better. Its 8088 runs at the proper 4.77MHz and above. Memory is much easier to expand, even in the original 1000 model. As an improved clone of the Jr, it features the same 3-channel enhanced sound and enhanced 16-color graphics (eventually becoming known as Tandy mode graphics). Unlike the Jr the Tandy 1000 is largely compatible with standard PC ISA cards and is for most practical purposes is 100% IBM PC compatible. Do yourself a favor if you’re looking for a capable early 80s PC and pass on the PCjr and pick up any Tandy 1000 instead, you won’t regret it.

IBM PC 300XL Model 6588

The IBM 300XL is a late 90’s PC from IBM that may look quite familiar to some of you. It uses the same case as the IBM PC 350 we covered on this blog way back in distant 2018. My first question is why did IBM use a model number that is lower than a previous model even though it uses a more advanced slot 1 motherboard as opposed to the socket 7 board in the PC 300. I guess that’s where the XL comes into the name, anyways….

On my 300XL if you look in the lower left hand corner my case is missing the cover for some unused ports. I’m guessing some models had audio jacks in this position. A little to the right of the center is the large beige power button and to the right of that is the sliding cover that when slid to the left reveals the drive bays. I have to say I do like the “Y2K Ready” sticker placed under the IBM logo.

Guess someone forgot to remove it.

Sliding the panel to the left reveals a single 3 1/2 bay and two 5 1/4 bays as well as one peculiar slim bay in the upper left corner I believe was reserved for a PCMCIA slot though there doesn’t seem to be an easy way to mount anything in this slot on my PC. My PC has a pretty standard combo of a 1.44MB floppy drive along with a CD-ROM drive.

Flipping the 300XL around reveals the ports on the back. There are five total expansion slots with four on the right and a single slot on the left coming off a riser card. At the center of the case we have two ports, a serial port and an IR port.

At the bottom of the case from left to right we have a number of jacks. Firstly are dual 3.5mm jacks for audio in and audio out for the built in sound. Next to this we have dual PS/2 ports for the keyboard and mouse followed by the parallel printer port. Next, we have dual USB jacks though it’s unclear if these are USB 1.0 or 1.1 as the user manual does not specify they are very likely 1.0. Lastly, we have an Ethernet port followed by a standard 15-pin VGA connector for the built in video.

The case of the 300XL is a screwless design and should come off by depressing the tab to the rear and pulling the upper casing off. On the underside of the case top should be a diagram of the motherboard along with jumper settings.

Here is my IBM 300XL with the case removed.

At about the center next to the CD and floppy drives is a mount for two hard drives. mine came with dual IDE HDDs one being 8GB and the other 2GB. Originally as I received it this PC had Windows NT installed but I did reformat the drive and installed Windows 95 OSR B. The power supply appears to be a fairly standard AT supply but features two extra power connectors that connect to the mainboard right behind the AT connector and another to the riser card.

Above we have the motherboard exposed with the riser card and mid support bar/HDD bays out of the way. The board is a proprietary board using the Intel 82440FX chipset. The board does provide sound in the form of a Crystal CS4236 chip providing sound blaster, sound blaster pro and WSS support though I was unable to locate any obvious crystal sound chip on the motherboard.

1 ) CPU – My 300XL came with a 233MHz Pentium II slot 1 CPU but also has jumper settings for installing a 266MHz Pentium II. The 300XL was probably a pretty early adaptor of slot 1 and although I havn’t tested this the 300MHz “Klamath” Pentium II would likely work as well. Later “Deschutes” Pentium II’s operate at a lower voltage which the 300XL does not appear to provide. Also Pentium II’s from 350MHz up also run on a 100MHz FSB which the 300XL also does not appear to be able to provide though provided voltage is not an issue could operate at a lower FSB and thus lower speed. The 233MHz PII is the slowest of the Pentium II’s but it should still make a capable CPU for most all DOS titles and early Windows 9x games. The CPU in my machine appears to get its cooling from a shroud directing air over the heatsink from a case fan.

2 ) RAM – The PC 300XL supports up to a maximum of 384MB of 168 pin DRAM memory. My 300XL currently has 96MB of memory installed. I’ve found many IBM PCs such as this one to be very picky about memory and none of my spare memory sticks worked on the 300XL even though they physically fit into the board. The manual states these specific memory requirements.

Must be 168-pin, unbuffered, +3 V type
Must have gold-lead tabs
Must have 60 nanosecond (ns) access speeds only
Must have a height of no more than 3.05 cm (1.2 in.)

3 ) Video – Built in video for the 300XL is provided by the S3 Trio64V2/DX and 2MB of DRAM. This chip is one of the later of the S3 Trio2D graphics chips. This makes an excellent video chip for 2D games and features top notch compatibility for DOS titles but lacks any 3D support. The chip does make sense considering the 300XL’s main purpose as a office or home work PC.

4 ) Riser – The 300XL uses a riser card to interface with any added expansion cards. The card features five 16-bit ISA slots (one on the oppose side) and three PCI slots though the PCI slots are shared with ISA for a total of five possible expansion cards.

The 300XL does not feature any AGP slot but something like a PCI Voodoo 3 2000 card as well as a good ISA sound card would be mostly all that’s need to turn this PC into a very capable DOS PC and even a quite adequate Win 9x gaming PC.

5) Piezo speaker.

The 300XL is basically a more powerful IBM PC 350 in the same case. The 2D video is slightly upgraded and it features the exact same amount and type of expansion slots so I’ll be a bit lazy here and quote what I said about that machine as it mostly applies here as well.

“The IBM PC 350 makes a fair retro computer. It excels at DOS retro gaming and needs very little besides an ISA sound card to have a very compatible machine. As a Windows PC it is quite acceptable and a PCI 3D accelerator card such as a Voodoo would do wonders. The BIOS tends to be fussy though and when I made ANY changes including simply unplugging the mouse the machine demanded I enter the setup feature upon restarting and change/save the new settings. There are other annoyances such as the extra connection needed on the power supply as well as the slightly picky 168 pin RAM slot.

The case itself is quite nice offering a sturdy design, decent bay expansion as well as being easy to get into. I also like the sliding piece on the front so you can cover up your ugly discolored drives when not in use. Adding drives though requires some disassembly and is a hassle.”

The main difference with the 300XL is the CPU and the switch from socket 7 to slot 1. The Pentium II makes for a much more capable processor and thus a more capable computer when it comes to being a Windows 9x gaming machine though at the expense of being able to install a much slower socket 7 CPU and have a more speed appropriate DOS PC.

IBM AT 5170 (8MHz)

The IBM AT also known as the IBM 5170 is IBM’s follow up to the IBM PC and IBM XT (and XT-286) home computer. Released in 1984 the 5170 featured a 286 processor and the then new 16-bit ISA expansion slots which would continue to be seen on computer motherboards all the way until the early 2000’s. The AT also supported high density floppy drives, came standard with a hard drive, featured a battery to store system settings as opposed to motherboard switches and was a great machine for then then new EGA graphics standard.

For the duration of this article please take not I will be using the terms 5170 and AT interchangeably to refer to this PC.

The IBM 5170 has a pretty utilitarian look in my opinion but there are many fans of the industrial look of this very sturdy case. My case was rescued from a garage and has some significant rust and scratching but it still fully functional. On the far left we have the standard IBM model badge as well as a lock and LEDs for power and hard drive activity.

On the right side of the case are dual 5 1/4 drive bays. These bays are usually populated by two 1.2MB 5 1/4 inch floppy drives though it’s fairly common to see at least one bay housing a 3 1/2 inch floppy drive via a bay adaptor. All 5170’s support 720KB floppy drives but later revisions like mine also support 1.44MB 3 1/2 drives. I did upgrade one of my 1.2MB floppy drives to a 1.44MB drive but keep in mind you will need a bay adaptor as well as a molex to floppy power adaptor.

Below these duals bays there is also a smaller bay obscured by the front panel that could possibly mount a smaller half height form factor hard drive.

Like the earlier IBM computers the AT power switch is a large red flip switch located towards the rear of the case and on the side.

Looking at the rear we see the power supply on the left side. The AT came with a PSU of about 200w which was sufficient to power a hard drive and several expansion cards and drives. The only built in port on the AT is the AT keyboard port located next to the expansion slots. The AT like the XT supports the now standard eight expansion ports which meant now you had to sacrifice less when picking and choosing expansion cards as the earlier PC only have five expansion slots.

After the five rear screws securing the case cover are removed we can take off the top and have a look inside the AT.

As seen in the image above my original configuration included three expansion cards such as the hard drive controller as well as a serial/parallel port card and lastly a cirrus logic VGA card. The VGA card will be replaced later for something more period correct for the 5170.

Below is a view of the motherboard with the expansion cards removed.

The hard drive is housed in a bay next to the dual 5 1/4 bays. The 5170 shipped stock with an unreliable 20MB MFM hard drive though at some point my AT was upgraded to a 40MB model.

The 5170 lacks any switch blocks on the motherboard and setup is accomplished via a setup program run from a floppy disk. There is an official IBM setup program but it can be a little outdated and the setup program itself may not have options for things such as 1.44MB floppy drives even though the motherboard may be fully capable. A good alternative is a program called GSETUP which you can use with the IBM 5170 as well as other computers which require setup programs.

1 ) CPU – Early versions of the IBM 5170 used a 6MHz 80286 for it’s CPU but later revisions like the one I have pictured were upgraded to an 8MHz 80286.

Even at 8MHz the AT’s 286 processor is on the slow side as far as 286 CPU’s go. It’s certainly faster then an 8088, even at 10MHz but it’s still to slow to be optimal for many VGA titles that are more action oriented like combat flight simulators. The earlier IBM XT-286 was said to run faster with the same speed CPU due to 0 wait states though I have never personally tested this.

2 ) FPU – The 5170 motherboard does have a socket for adding a 287 math co-processor to assist in more complicated mathematical processing.

The FPU is useful for CAD type programs but it’s usefulness in games is quite limited with only a scarce few games of the time taking advantage of the processors capabilities.

3 ) RAM – All IBM AT’s came standard with 512KB of memory on the motherboard. The 5170 supports up to 16MB of memory though expanding to a full 640KB and beyond does require a memory expansion card.

4 ) Battery – The 5170 motherboard does not have any CMOS battery on the board to save settings nor switches (besides for monitor selection) thus a working battery is essential to save the settings set with the previously mentioned setup programs. The 5170 in order to save settings uses an external battery.

As original batteries are long dead for the most part buying a newer replacement will most likely be required. There are many options on eBay that use AA batteries though usually the wiring is keyed differently. Modification will most likely be required as most of these battery holders are not wired for the AT.

There is a switch between the power connector and the external battery connector. This switch is for selecting the monitor in use. The rear position is for using an MDA monitor and the forward position is for CGA. The position has no effect when using an EGA or VGA video card.

5 ) AT Power Connector

6 ) PC Speaker – The 5170 has a fairly decent PC speaker located at the front of the case.

Let’s take a look at the expansion cards I have installed in my IBM 5170 making it a late 1980’s configuration.

We will start with the two cards my PC had preinstalled and not counting the VGA card I initially installed for testing.

Hard drive controller

I believe this WD based 16-bit MFM controller card which came with my 5170 is the stock card provided for the later revision 8MHz AT’s.

The other card that came with my 5170 was a simple serial/parallel port card which is extremely useful seeing as there are no built in I/O ports.

And now to take a look at the expansion cards I decided to add.

Joystick Card

I decided to add a gameport card since my soundcard of choice did not have a gameport on it as many later sound cards do.

The card I went with was an 8-bit CH Gamecard III automatic. I didn’t have any specific reasons for choosing this card other then it’s what I had on hand although it is nice that it supports two gamepads.

RAM Expansion

Having memory over 640KB isn’t to important on an IBM AT since most games that will run acceptably on this PC only require 640KB or less of conventional memory. Unfortunately the 5170 only came with 512KB of memory stock so although that is enough to play a number of games you really want to get a full 640KB to get the best experience with the AT.

For memory expansion I installed an Intel Above Board which has a total capacity of 2MB but also allows you to backfill the conventional memory to the full 640KB bringing the total memory of the 5170 to 640KB of conventional memory and the difference allocated to being XMS or EMS memory though usually XMS is favored for 286 class PCs. Larger memory cards are available and you can even install multiple cards up to 16MB but I’ve found little use for more then 2MB in a PC of this vintage and class.

Audio

Sound cards weren’t really a thing until 1987 and most games that will run on the 5170 well won’t necessarily require anything beyond PC speaker though a sound card does expand your options. Since I decided to go more period correct with this PC I decided an original Adlib was the best choice.

The original Ablib as seen above from 1987 uses a 1/4 inch audio jack and a simple volume knob. This card uses off the shelf parts but its YM3812 FM chip is widely supported in games. These cards are quite the collectors item these days so I can’t recommend tracking one down unless you want a strict period correct machine from the later 1980’s and have large sums of cash to burn. Almost all later sound cards like the Sound Blaster 16 have perfect Adlib compatibility so I would suggest more people go down that route. There are also a number of Adlib reproductions available for a much cheaper price if you want to keep that original Adlib look. Later Adlib cards from 1990 also switched to a more commonly used 3.5mm audio jack.

Video

In the late 80’s most 5170’s would likely have been fitted with an MDA or CGA video card though the more expensive and fancier option was the official IBM EGA card allowing 16 colors on screen at once.

There are later smaller and cheaper EGA cards with all the memory built in but the official IBM card just felt right for this PC. The IBM EGA video card only comes with 64K of video memory on the card severely limiting resolutions and colors on screen and causing some games to display an incorrect image. There is a memory expansion daughterboard as seen above which brings the card up to a full 256K of video ram. These daughterboards used to be quite rare though I believe there are third party replacements available. I unfortunately only have a CGA monitor on hand but thankfully the card can be made to display to a CGA color monitor via switches on the card and will display EGA graphics but at a lower resolution.

You can add an ISA VGA video card which would be significantly cheaper and allow the use of much more common VGA monitors if so desired though I find this much less interesting.

Overall the IBM 5170 is a capable PC for the 80’s although I do feel its CPU is a bit on the weak side even at 8MHz speeds. It’s to fast for very early PC games that require an 8088 CPU but for more demanding games of the 80’s a 12MHz or 16MHz 286 or a 386 would serve you much better. I went with a very IBM, period correct build for this article but nothing is stopping you from adding a decent VGA card and Sound Blaster 16 giving a significant boost to this PCs power and expanding the playable game library, though as I mentioned the CPU will still be a bottleneck for more demanding VGA games. In my opinion one is better off with a clone system which are usually smaller, lighter and have more things built in such as more memory and I/O ports. You also most likely do not have to worry about the tiresome setup programs required on the 5170 when using an IBM compatible which is a plus. If you are an IBM fan though this PC can be a lot of fun. The design is seen as beautiful by many IBM enthusiasts the AT is more expandable and versatile then the IBM PC and XT and the case itself is built like a tank.

IBM PC 5150

There were personnel computers before the IBM 5150 but the 5150 is the computer that solidified what an IBM compatible PC would be. The 5150 featured an x86 processor, internal slots for various upgrade cards and was primarily intended to run off of PC-DOS / Microsoft MS-DOS operating system, all things we would learn to associate with the future IBM PC compatible market. The IBM 5150 was released in 1981 and was primarily intended as a machine for serious business tasks but was certainly capable of playing games and performing other non business functions.

The overall construction of the 5150 is extremely sturdy with a heavy metal case. The face of the case features no buttons or LEDs that we expect from later PCs and just features a stylish IBM PC badge, some vents and dual full height drive bays. The 5150 was sold in a few configurations including dual and single floppy drive variations as well as a version with no drives at all.

The dual full height bays commonly housed one or two 160k/360k (single/double sided) floppy disk drives. You can add two half height drives into these bays though this will require some means to secure the mounting as the bays are designed only to secure full height drives.

The power button is located on the left rear side of the 5150 case and uses a large on/off switch.

A locking mechanism was sold by IBM which one would place over the power switch which allowed the PC to only be turned on with the use of a key though I believe this also worked with XT and AT models as well.

Lets take a quick look at the rear of the case.

On the left side we have one female and one male power port. the male connector uses a standard three prong power cable with the female connector intended for a monitor to to plug into. To the right of the plugs we have a large round vent for the power supply followed by a keyboard and cassette connector. On my PC these ports are conveniently labeled.

The original keyboard for the IBM 5150 is the model F.

Model F keyboard

The model F is similar to the later model M in that it is very well built and does feature “clicky” keys. As you can see above the function keys are located to the left and there is no space between the num pad and the rest of the keys. This is a PC/XT class keyboard and will not work on later AT class machines.

The cassette port located next to the keyboard port was rarely used on the 5150 though I suppose if one had purchased a variation without any disk drives this would have been the expected method of data transfer. Finally we have five slots for adding expansion various cards.

Before opening this case up and looking inside lets take a quick look at the monitor.

The intended monitor for the 5150 was the IBM 5151 green monochrome monitor. Being mostly intended as a machine for office use where sharp text took priority over color, although IBM did release a color CGA and EGA monitor with very similar styling. The 5151 monitor gives a very nice and sharp monochrome image and is also surprisingly light compared to the general heft of the 5150. The two dials are for controlling brightness and contrast.

Unfortunately the two power cords on the 5151 are hard wired to the monitor itself. One cord is a 9-pin connector to connect to a monochrome video card with the other being the power connector intended for connecting to the female plug on the 5150’s power supply. There is no power button on the 5151 as the monitor was intended to power on with the 5150.

OK, now lets take a look at the inside of our 5150.

Take note that I have upgraded the power supply in these images to a 130w power supply in order to accommodate a possible hard drive. The stock power supply in the 5150 is a fairly anemic 63w supply and may not supply enough power if a hard drive is added.

There were two motherboard versions released for the 5150 depending on when it was manufactured. Earlier models used the 16kb-64kb boards which only were capable of supplying a maximum of 64kb of RAM on the board’s RAM sockets. My 5150 uses the later 64kb-256kb motherboard indicating a total of 256kb of RAM could be installed on board.

1 ) CPU – The CPU is the classic 8088 running at 4.77MHz. This was a cost saving measure as the 16-bit 8086 would have been faster but more expensive. Keep in mind that the NEC V20 which offered a slight speed boost over the 8088 was a fairly common upgrade on these machines.

1.5 ) math copro – Located alongside the CPU socket is the FPU socket for adding an 8087 math co-processor if desired.

2 ) RAM – My PC has been upgraded to the full 256kb of memory. Notice how the first row of memory is directly soldered to the motherboard while the following three rows are socketed.

3 ) PC Speaker – The 5150 uses a real PC speaker located on the far side of the case.

4) Switches – Two switch blocks located on the motherboard are used for setting things such as installed memory, type of video card installed ect… switch settings as well as a large amount of other information on the 5150 and other IBM PCs can be found here.

Lets take a look at the various expansion cards I have installed in my 5150.

Unlike later IBM PC compatibles which upped the standard expansion slot count to eight the 5150 only sports five 8-bit ISA slots. This can be a little limiting considering there is virtually nothing built in as far as video and I/O goes as well as the fact that your going to most likely be losing one ISA slot right from the start to a floppy drive controller card.

This is the standard IBM floppy controller. It features an external floppy port and when paired with the 5150 can support up to four floppy drives. Drives connect via the edge connector on the rear of the card. This card is currently running my dual 160k/360k drives but is also capable of supporting 720k 3 1/2 inch floppy drives.

Next up of my currently installed cards we have the monochrome video / printer card.

The IBM monochrome monitor card (MDA card) is designed to connect to the 5151 monochrome monitor and you will usually find this card installed in almost all 5150’s. The MDA card is not capable of displaying pixel graphics but only characters thus making it largely unsuitable for games but great for business which mainly benefited from having a sharp text display. There are games like Rogue which can be played on an MDA monitor since it only uses text and characters for graphics. Thankfully IBM understood the situation with limited expansion ports so the IBM MDA card also included a printer port.

An option even better then the IBM monochrome card would be a Hercules card or Hercules compatible card. These cards also worked with a monochrome monitor and featured a parallel port but also had the added benefit of being able to display graphics on a monochrome monitor for games which supported Hercules mode and with a small program even emulate CGA graphics in monochrome.

Thankfully you could also install a CGA card (as well as an EGA or VGA card) in the 5150.

There are a few revisions of this card from IBM with minor differences but I am using a later revision here. Although you can install a EGA and even some VGA cards in the 5150 I find the machine lacks enough power and RAM to properly run those sorts of games and is best suited for playing CGA titles. There are also a number of later more advanced CGA cards from companies like ATI which offer more display modes in a smaller form factor but I was trying to keep things more or less IBM and early 80s with this build.

Most commonly CGA offers games to be played with four colors from just a few palettes. Black, Cyan, magenta, white is the palette most associated with CGA though there are other palette options.

The IBM CGA card also offers a composite out for connecting to a standard TV. This produces a less sharp image then CGA on a computer monitor but techniques like dithering can be used to blend colors and create an image resembling EGA in some cases.

You also have the option, like I have done with my 5150, of installing dual video cards. I currently have both a MDA and CGA card installed. You can switch back and forth between MDA and CGA monitors with a DOS command MODE CO40 for CGA 40 column mode, MODE CO80 for CGA 80 column mode and MODE MONO for the monochrome display in 80 column mode.

The final card I have installed is an AST MegaPlus II card.

multi function cards like the MegaPlus II and the AST SixPack Plus were fairly common for the IBM 5150. The lack of expansion slots gave an opportunity for third parties to step in and create expansion cards which incorporated several useful features into one card. The MegaPlus II adds a real time clock, up to 512kb of memory to bring your 5150 up to 640kb, a serial port as well as multiple headers for daughterboard expansions.

Adding a hard drive / 720kb floppy drive

I kept my 5150 fairly stock and period correct but for some extra quality of life adding a hard drive and 720kb floppy drive is fairly simple.

The first issue you’re going to have with adding two half height drives is that the bays were only designed to securely mount a single full height drive as we can see in the image below.

Any upper drive would have no points to mount to. Thankfully there are some solutions as mounting plates were made to allow the use of dual half height drives. Theoretically I suppose if you had some sheet metal and tools you could create your own mounting plates. Below is a mounting plate I used, unfortunately it has no labeling so I’m not sure if it was homemade or part of some official kit.

If you do not have a mounting plate I found improvising works just as well though may it may not look as eloquent of a solution. I was able to position a mounting rail from a random PC diagonally and use it as a fairly sturdy mounting solution.

Once the mounting situation has been taken care of its time to well….mount the drives. Mounting the 3 1/2 720kb is fairly simple as even the stock IBM floppy controller will support it. You just either need a cable with the correct connectors or install a pin to edge connector adapter on your 720kb drive and it should run just fine. Newer 1.44mb drives will also work as 720kb drives without issue.

Installing a hard drive is a little trickier as the stock power supply is under powered for the task and the 5150 was not initially designed with a hard drive in mind as IBM never offered a hard drive as an option although later it did offer a 5161 expansion unit which did house a hard drive but which was the size of the entire 5150. Your first task is to upgrade the power supply with a beefier one. I upgraded mine to a 130w supply.

If you want to be more period correct you will want a MFM or RLL hard drive controller. I used a WD controller as well as an ST-225 20MB drive which worked without issue for me.

If your not trying to be period correct your best bet would probably be an XT-IDE controller with a CF card as these draw much less power then period drives and offer much faster speeds and reliability.

A friend once asked me why I would want a 5150 and proceeded to ask me if I “wanted to emulate being a 1980s office worker”. This comment is actually pretty fair since the 5150 is first and foremost a business machine. You certainly can play games on it and with a little work upgrade it well for this purpose but in truth there are many better options if you’re looking for an early 80’s 4.77MHz niche machine. The weak power supply and limit of five expansion slots does not do the 5150 any favors. If you want an early 80’s 8088 based machine find or build a nice machine with eight slots a turbo button and 640kb of memory built in.

On the other hand as a collector of vintage PC hardware the 5150 is a no brainer, it needs to be in your collection. The 5150 is iconic and set the stage for all IBM PC compatibles for decades to come.

IBM 300PL Type 6862

Around four years ago I wrote an article on this blog about the very similar IBM 300PL Type 6562. I picked up this machine because I really liked the style of the case but it really wasn’t the model I was looking for. Finally, several years later I finally acquired my IBM 300PL 6862.

The case is more or less identical in style and size to the 6562 except it lacks the audio input/outputs and volume control under the floppy drive. On the left side of the case we have a large power button with three LED indicator lights underneath for power, HDD activity and network activity. Near the center of the case is a slot meant for a 1.44MB floppy drive. To the right side of the case we have 2 5 1/4 drive bays with one being occupied with a CD-ROM drive, though in this case it is not the original drive.

Turning the case around we can tell right away by the orientation of the four expansion slots that this machine uses a riser card. Starting under the expansion slots mid-case and moving right we have our various built in I/0 ports. First we have three audio jacks for the built in audio for a microphone, line in and finally line out. Next we have an Ethernet jack followed by a parallel port, dual USB 1.1 connectors, dual serial ports, two PS2 ports for mouse and keyboard and lastly a VGA connector for the built in video. Above the VGA port is another unusual cutaway. This is for the possible addition of an AGP card which we will take a look at once we are inside the case.

The case lid is pretty easy to remove and just requires lifting two tabs at the back of the case and pushing it forward and up. The IDE hard drive is mounted out of sight below the CD-ROM drive and below the second 5 1/4 bay.

Here is the handy data sticker found on the underside of the case cover though note that I found it wasn’t 100% accurate which we will talk about. This may be due to me updating the BIOS to the latest version.

And next lets take a better look at the motherboard.

The motherboard is an NLX form factor board which some manufactures like IBM and Intel pushed in the late 90’s. It was meant to be a low profile, low cost motherboard form factor and had some odd quirks like the AGP port placement on this board which is located far from the other PCI and ISA slots and, for the most part, requires NLX form factor video cards. It’s a little hard to see in the images above but the motherboard connects to another brown colored edge connector located where the riser slot is located.

1 ) CPU – The Type 6862 motherboard uses a slot 1 socket and supports both Pentium II and III slot 1 CPU’s. My particular machine came with a 450MHz Pentium III, the lowest clocked Pentium III, and also had what I’m pretty sure a cooling fan added on by the previous owner.

The sticker on the underside of the case lid gives switch positions for installing a Pentium III up to 550MHz but with an update to the latest BIOS I was able to successfully upgrade the CPU to an 800MHz Pentium III and using a Power Leap adapter was even able to install a 1.3GHz Tualatin. A few things to note however is I found the switch settings useless when upgrading the CPU and when I changed them from what was the systems default I even ran into POST errors. I suspect this may be an issue caused by the BIOS update which changes how CPU speed is handled. I did however run into a separate POST error after changing CPU’s that I had to go into the BIOS advanced features menu and disable “CPU BIOS update”.

Also note that there are no power connectors on the main motherboard for the CPU fan but there is one on the riser board which can be used.

2 ) RAM – The Type 6862 officially takes up to 384MB of PC100 SDRAM. My machine was able to recognize 512MB with the BIOS update under Windows 98se. I am currently using two 256MB sticks of PC133 which work at PC100 speeds on this motherboard.

3 ) Video – The built in video chip is a S3 Trio 3D with 2MB of SGRAM. The Trio 3D is more or less the successor to the Virge line of 3D acceleration chips and like them it has great 2D compatibility with older DOS titles but 3D is somewhat lacking. For retro gaming I strongly suggest upgrading with an AGP card unless your strictly going to be playing 2D titles.

4 ) Sound – Sound is provided by a Crystal CS4235-KQ chip. I don’t have much experience with this chip but the datasheet indicates it is Sound Blaster, Soundblaster Pro and Windows sound system compatible though being a budget chip I wouldn’t be surprised if the FM synth was not up to par with a true Yamaha OPL chip. For general use in Windows it should suffice but if you want to use the 6862 for gaming I would advise disabling the built in sound and adding an ISA or PCI sound card depending on your needs.

5 ) As was mentioned earlier the Type 6862 uses a riser board like many Desktops. on this riser board we have various connectors such as the power connector for the CPU fan as well as three PCI and two 16-bit ISA slots. This should be more than enough for adding sound and video cards depending on your needs.

If you look below the riser you can also see the long brown slot the motherboard itself connects to.

When installing expansion cards each card does not get its own screw to hold it in place but the case used a metal bracket that unscrews and then screws back on to secure any added cards.

6 ) AGP slot – Unusually on this board the AGP slot is located far away from the riser card and the other PCI/ISA slots. On a technical level it does not make much if any difference though it can cause issues if you were hoping to run a certain setup such as using a Voodoo 1 or 2 or any card that requires some sort of cable connection to your primary video card.

The other issue this arrangement causes is that due to the special video backplate used you need an NLX compatible video card with its video connector high on the card. Usually, these cards also have a little square cut on on them on the lower half under the video connector.

NLX compatible card on the right along with bracket adapter. None compatible card on left.

Thankfully Diamond Multimedia made a large number of NLX compatible video cards and most late 90’s video chips can be found in this form factor such as the Voodoo3, TNT 1 and 2, Matrox G200, ATI Rage 128 and others. The most powerful card sold in the NLX form factor was the Geforce 256 SDR though they tend to sell for quite a large amount of cash these days.

ATI Rage 128 in NLX form factor and proper bracket adapter attached.

I quite like the IBM 300PL Type 6862 and it’s quite versatile. You can easily install a low clocked Pentium II along with an ISA sound card and have a fast DOS rig. On the other hand, it also makes a great Windows 9x retro PC depending on your era of choice determined by your CPU and video/sound card choice. The ability to support everything from a Pentium II 233MHz all the way up to a 1.3GHz Tualatin via a power leap adapter makes this a very versatile retro PC.

The case is a bit large however and does take up quite a lot of desktop space. Other annoyances such as the odd arrangement of the AGP slot slightly limit your video card options but despite this the 6862 makes a great late 90’s retro PC.

IBM Aptiva model 2176-C77

In the year this article is being written (2019) what company comes to mind when you think of “Personal Computer”? Dell? HP? Gateway? possibly a maker of computer components like Asus? Well in the ’80s the answer would very likely be IBM.  IBM set the standard for the early personal computer with the model 5150 and continued to be a force in the home computer market for some time. By the late ’90s though IBM had started to withdraw from the home PC market and the average home computer buyer was more likely to think of companies like the aforementioned Dell or Gateway 2000 (as they were known at the time) when shopping for a PC. Today we are going to take a look at the IBM Aptiva model 2176 from the mid 90s and see what IBM had to offer to the home market in those later days.

The Aptiva 2176 is actually a pretty nice looking tower and for the day stood out with a unique looking design. At the top we have a large square power button with two LEDs for power and HDD activity located to the left. Lower down we have the classic IBM badge and of course that large sturdy handle on top that pretty much every tower of the day lacked giving the case its own look.

Pressing the large blue button on the upper left releases the upper cover which slowly and oddly satisfyingly slides down to reveal the drive bays.

There is room for two 5 1/4 drives as well as two of the 3 1/2 inch variety. I still have the original configuration of one 1.44MB floppy drive and the original 8x speed CD drive.

Turning the PC around and taking a look at the back.

On the back we have a curious indent near the top of the case and it took me a little while to realize that this was actually a grip for your other hand when using the handle at the front of the case to transport the Aptiva.

Under the power supply we have an odd jack with a sticker next to it showing a speaker and 12V. This is actually a pretty handy jack for powering certain external speakers, thus freeing up a socket on your wall or power strip. I’m surprised I’ve never seen this handy addition on any other PC case.

Below this we have a hefty eight expansion slots with various connectors lined up to the left of these. First of these connectors are two standard PS/2 ports for keyboard and mouse. This followed by a serial port and a single USB 1.0 port. The Aptiva 2176 is one of the earliest OEM machines I know of to feature a USB port. Lastly we have a standard printer port and a VGA port for the built-in video.

The case can be opened by unscrewing two screws at the top of the case near the handle to the front and then pulling back on the cover.

My Aptiva appears to of been mostly left stock upon taking a look inside. The first thing you notice is the odd riser board obscuring a majority of the motherboard which IBM used for this Aptiva. We will take a look at this after a quick look at the hard drive.

My machine came with the original 3.2GB hard drive installed. The hard drive on this model is installed in a small 3 1/2 inch bay directly above the power supply, thus leaving the frontal drive bays free. The built-in EIDE controller supports up to mode 4.

Let’s go back now and take a closer look at the riser board.

The riser board has one AUX style power connector connected to it and is pretty unique in its design having two PCI slots between two separate sets of 16-bit ISA slots, two ISA above and four below for a total of six ISA.

I find the choice of only including two PCI slots on a socket 7 Pentium class motherboard intended for a Windows OS especially odd. At the point the Aptiva was released PCI was certainly seen as the primary expansion style slot of the future and limiting the board to only two slots seems a tad short-sighted, especially when we consider that even 486 class motherboards that had PCI had at least three of the slots. The lack of PCI isn’t much of an issue if you intend to use the Aptiva as a DOS machine but could be limiting if you wanted a more capable Win9x PC. Thankfully having integrated graphics does alleviate the issue a small amount.

Here we have the motherboard with the riser board removed.

1) CPU – The motherboard is a socket 7 board and from what I could tell the model 2176 came with either a 166MHz or a 200MHz non-MMX Pentium CPU. My Aptiva came with the 166MHz Pentium non-MMX installed along with a fanless heatsink (though a case fan was nearby).

Officially the model 2176 only supports up to a 200MHz non-MMX but I’ve read from other sources that some individuals have had success with installing a 233MHz MMX CPU as well as later 333MHz K6-II CPU’s though you may encounter issues with the BIOS not reporting the correct CPU on POST. Installing a later K6 CPU may also require a voltage regulator that can support lower voltages. The regulator can be seen in the image below located above the CPU socket. I haven’t experimented with later CPU’s myself so I take no responsibility if you try later CPU’s though I would guess getting a 233MHz Pentium running by setting the multiplier to 1.5x to get 3.5x 66 = 233 along with a decent heatsink/fan wouldn’t be much trouble.

2) RAM – The model 2176 can accept a maximum of 128MB of memory via either a single 168-pin socket or four 72-pin sockets. I currently have 64MB of memory installed via a pair of 32MB 72-pin SIMMs.

3) L2 cache COAsT slot – The 2176 motherboard uses a COAst module or Cache On A SticK for L2 cache. The board can accept either 256KB or 512KB modules though mine has the seemingly more common 256KB module installed.

4) Video – The on-board video chip for the Aptiva 2176 is the ATI 3D Rage  chip with 2MB of memory. The 3D rage was more or less ATi’s Mach64 2D core with some 3D capabilities and MPEG-1 acceleration tacked on. As a 2D chip it does a decent job with Windows acceleration and has decent DOS compatibility. As a 3D accelerator through the first Rage is pretty lacking which is understandable seeing as this is a pretty early 3D chip. I tested a few games on this machine and found Tomb Raider playable but the sequel was missing textures. I wouldn’t expect great compatibility with 3D games past the 1997 or so mark even if you max the RAM in this system and beef up the CPU. I’d definitely recommend using one of those PCI slots for a video card upgrade.

Before moving on though I will say I found the Aptiva 2176 a bit picky when it came to video card upgrades. Some of the more “quirky” accelerator cards such as the Rendition Verite that may require some BIOS tweaking simply would not work with my Aptiva despite upgrading to the latest BIOS. A Matrox Millenium card however installed without issue.

5) Riser card connector – This is the slot for connecting the riser card. The slot uses edge connector pieces to make the connection. These edge connectors are not secured to either the slot on the motherboard or the riser card so if you do remove the riser card you may get a piece or two that stays stuck to either the card or the board. as you see below.

6) VRM – This is the voltage regulator module. I mostly see these on socket 5 and Pentium Pro and early socket 7 boards and are used to control the voltage to the CPU. If you want to use a CPU that requires a lower voltage make sure your installed VRM is capable of supplying that lower voltage.

7) This is the voltage regulator for the external 12v speaker jack

8) AT power connector

9) piezo speaker

Even though sound was not built into the motherboard IBM supplied every Aptiva 2176 with the infamous Mwave sound/modem combo card also known as the “Dolphin”.

The card is a 16-bit ISA combination sound card/modem. The card features IBM’s Mwave digital signal processor and a chip from Crystal. The Mwave is sound blaster compatible and has midi capabilities. The modem part of the card is quite interesting since it is a 28.8k modem software upgradable to 33.6k. Unfortunately the card had many issues and was infamously buggy, especially when using both the sound and modem functions. This was so bad a class action lawsuit was filed against IBM and the card was quickly dropped on later models.

I wanted to experience the sound capabilities of the Mwave myself so I installed the sound card drivers and left the modem drivers uninstalled. Doing this I had a pretty stable experience with the card overall.

There is a later plug and play version of the Mwave called the Stingray but for my non-plug and play Dolphin version Windows did not detect the card on install. The 2176 originally came with Windows 95 though I had upgraded my Aptivas OS to Windows 98SE and the drivers for the Mwave needed to be manually installed off of the Windows 98 installation.

Control Panel > Add New Hardware > No, I want to select hardware from a list > scroll down to “Other Devices” > in Manufactures select IBM and in Models select “IBM Dolphin Mwave DSP adaptor”

Doing this will give you basic sound functionality in Windows. Sound in DOS may take some extra steps to set up but this will give basic Windows sound support. The midi capabilities at this point are pretty bad and require an extra step.

For full midi support you’re going to need to find and download the Mwave midi samples on the internet and install them to C:\Mwave\Samples\Midimed

You can simply drag and drop the files to the specified folder and I found the midi capabilities of the card to be quite adequate after installing the samples.

The IBM Aptiva model 2176 isn’t a bad computer overall once you deal with its quirks. These things were quite expensive in their time and I wouldn’t have found them a great value when new but as a retro PC you can do a lot worse. The case is actually quite nice and stands out a bit from the other beige towers with its handle and sliding drive panel. There are some odd choices such as the riser board and the severe lack of PCI slots. The lack of PCI slots can hamper any thoughts of adding a new video card and a pair of Voodoo 2’s in SLI along with a USB 2.0 card and an ATA-133 controller (all at once) but I’d strongly suggest at least ditching the Mwave for another PCI or ISA sound card (depending if your leaning more DOS or Windows gaming) and bypassing the 3D Rage chip for a more capable PCI video card.

 

IBM PC 350 model 6587

The IBM PC 350 was released in the mid 1990’s as an office / home desktop PC. It came in several sub models that used completely different motherboards and CPU’s from a socket 3 486 class up to socket 7 Pentiums all using the same case. In this article were going to look at the sub model 6587 which is the last sub model in the PC 350 class.

The case for the PC 350 is both sturdy but at the same time not extremely heavy. On the front there are LED lights for HDD activity and a power LED next to the large white power button. There is no reset button.

One pretty cool feature is the sliding front cover that slides to the left revealing your various drive bays. There is room for two 5 1/4 inch drives as well as a 3 1/2 bay and two internal 3 1/2 bays for hard drives. In the upper left corner is a cut out for an optional PCMCIA interface which I’ve never seen on a desktop before. Unfortunately mine did not come with this option installed.

My PC 350 did come with an 850MB hard hard drive installed which sounds about right for the time. A CD-ROM drive was an option but mine did not come with one installed. Installing a 5 1/4 drive can be a little taxing and removing the bay bezels can require a lot of force or completely removing the metal drive holders inside which also is not easy due to the assembly being held in by a hard plastic screw.

On the back we have from left to right, a infrared port for connecting an infrared receiver for wireless inferred communication with compatible devices. Next we have two PS/2 ports for keyboard and mouse followed by a serial port, two USB 1.0 ports and a parallel port. Lastly there is a VGA port for the built in video.

There are no screws holding the upper case on and accessing the motherboard is achieved by depressing the plastic tab in the upper left corner of the case and pulling back and then up on the upper case. Thankfully this tab is made from pretty rugged and thick plastic and feels fairly resistant to breaking off.

On the underside of the case is a simple chart explaining the memory configurations as well as a basic motherboard layout and the various switch settings. I always like when PC’s do this as it helps greatly when making basic changes like CPU upgrades.

Here is a view of the drive bay assembly removed from the case as well as the hard plastic screw that needs to be removed to get the metal assembly out.

Now lets take a look at the motherboard and relevant parts.

The PC 350 motherboard does use a standard lithium battery to store CMOS settings. In the image below is is obscured by the IDE cable.

 

1) CPU – My model 6587 came with a Pentium 133 but is easily upgradable. The chart found on the case underside gives settings for installing up to a Pentium 166 but online sources indicate a Pentium 200MHz classic or even a 166 or 233MHz MMX chip can be successfully installed though you may need to experiment with motherboard switch settings (Wikipedia suggests the 75MHz setting should work for 233MHz).

The MMX chips take a lower voltage from what it appears the board can provide so use caution if your going to attempt an MMX install. For a Pentium 200 classic the jumper settings were not present on my jumper sheet but through trial and error I found the settings for the Pentium 120 allowed for 200MHz operation with the P200.

The CPU’s on all of these machines are fanless and only come equipped with a passive cooling heatsink, though a rather tall one.

The instructions and all paperwork only refer to 3.3 volt Intel Pentiums CPU’s being compatible with some sources claiming Cyrix and AMD chips to be incompatible though I was able to upgrade my board with an IBM branded Cyrix 6×86 PR 166+ CPU without issue. I just made sure my CPU was labeled as requiring 3.3 volts (most Cyrix 6×86 CPU’s seem to require only 2.9 volts).

ibm350cpuchart

*Correction* The above chart refers to the Cyrix / IBM CPU as a “PR 166+” as it should be labeled as a P166+

2) RAM – The PC 350 has one 168 pin RAM socket as well as four 72 pin RAM sockets for memory expansion. You can expand the memory up to a total of 192MB and the convenient chart found on the underside of the case lid has a graph showing the advised memory configuration for the desired memory amount.

My PC 350 came with 32MB of memory installed via one 16MB 168 pin stick and two 8MB 72 pin sticks. I originally thought I would try using a single 32MB or 64MB stick of 168 pin memory and forgo the 72 pin sticks but none of my 168MB sticks would physically fit the 168 pin slot. I tried several sticks and they all were physically very slightly off and would not install. This is because I later discovered the 168 pin slot is keyed for 5 volt SDRAM which is not compatible with the 3.3V (the common used SDRAM).

3) L2 cache slot – L2 cache on the model 6587 is via a COASt module fount next to the CPU and can accept either 256KB or 512KB of L2 cache. Mine came with a 256KB stick though I needed to remove it and clean the contacts before it was recognized.

4) Video – The PC 350 comes with a S3 Trio64V+ chip on the board along with the ability to expand the memory from 1MB up to 2MB. The Trio chipset is an extremely DOS compatible chip proving excellent 2D support and compatibility for DOS and Windows 9x.

5) Riser card – The PC 350 uses a riser card in order to provide both PCI and 16-bit ISA expansion slots. In total the riser provides three PCI and five ISA slots though three slots are shared PCI/ISA slots and two are dedicated ISA slots. The opposite side of the riser provides for one of the stand alone ISA slots as well as a connection for power.

6) Floppy/IDE -The 350 motherboard provides for standard floppy connection as well as two built in ATA-2 IDE connectors for a total of four IDE compatible devices.

7) Switch – This is the switch used mainly for selecting your processor speed. Thankfully the chart on the underside of the case provides the settings and switch configurations should you decide to change CPU’s. The chart provided does come off as a little confusing though as It does not list actual FSB settings or provide a setting for 200/233mhz CPU’s. The Wikipedia entry on the PC 350 advises setting the switches to the “75 MHz setting” for a 233MHz Pentium.

8) PSU – The 350 motherboard requires three PSU connections to the board. Besides the standard AT connection the 350 also requires an additional AUX connection as seen below.

The IBM PC 350 makes a fair retro computer. It excels at DOS retro gaming and needs very little besides an ISA sound card to have a very compatible machine. As a Windows PC it is quite acceptable and a PCI 3D accelerator card such as a Voodoo would do wonders. The BIOS tends to be fussy though and when I made ANY changes including simply unplugging the mouse the machine demanded I enter the setup feature upon restarting and change/save the new settings. There are other annoyances such as the extra connection needed on the power supply as well as the slightly picky 168 pin RAM slot.

The case itself is quite nice offering a sturdy design, decent bay expansion as well as being easy to get into. I also like the sliding piece on the front so you can cover up your ugly discolored drives when not in use. Adding drives though requires some disassembly and is a hassle.

For a DOS PC the IBM PC 350 will serve you well though for Windows it’s passable but there are much better options. As a side note I could not get Windows 95 or 98 to install on my machine. This was due to some sort of driver conflict at the Windows splash screen I was never able to resolve. The machine IS Windows capable however and this problem boiled down to my particular machine.

IBM 300PL Type 6562

There’s just something about an IBM machine. After the PS/1 and PS/2 line IBM continued within the consumer PC market with a line simply known as the IBM PC line. This line of PC’s was sold roughly from 1994 to 2000 and consisted of many models from mid range 486 CPU’s to Pentium III’s. There isn’t anything particularly special about the IBM PC line as they don’t do anything necessarily new outside of a few uncommon design choices though I have to say I’ve always loved the look of the desktop cases within the line. In this article we are going to look at the 300PL type 6562…..sounds like a designation for a WWII Japanese tank.

ibm300pl1

I’ve just always liked the look of these desktops. Kind of unique look that mixes more modern style (late 90’s and 200’s) with older (80’s early 90’s). The only thing I really don’t care for is the plastic case seems pretty fragile in parts and mine received a fair amount of damage in shipping. We have sort of a “ribbed” beige case with a nice prominent IBM logo. To the left we have a large round power button as well as your led lights for power, HDD and Ethernet. Not to much room for external bays as we have a spot for a 1.44mb floppy mid case and to the right of it two 5 1/4 bays that I currently have a DVD drive installed in one and nothing in the lower bay. Stock this machine would have a CD drive installed rather then a DVD drive.

One feature of the type 6562 that is lacking on most other models of the 300PL line is the convenient front audio options.

ibm300pl2

We have a microphone jack and a headphone jack as well as a very convenient volume knob. My research indicates this was removed from later models due to the fact it was difficult to line up the case with the volume knob when putting the case top back in place though personally I have not found this to difficult. The built in audio is powered by a Crystal 4236B chip. It is possible to enhance the audio quality of the sound by replacing some caps but I will leave a link outlining this processed at the end of the article.

Looking at the back.

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You may notice in the image above that the case uses plastic tabs to shut which unfortunately were damaged in shipping so the case doesn’t quite snap back together properly. There are four expansion slots arranged in a vertical manner as well as a key slot for locking the machine if you were the type to do such things. Its inclusion does make sense seeing as these were likely heavily marketed to business. Starting at the lower left we have the usual suspects, audio in and out jacks along with built in Ethernet port, parallel port, two USB ports, two serial ports, ps/2 ports for keyboard and mouse and finally a built in VGA port. Having built in Ethernet and audio out of the box is a nice feature for a Pentium 1 machine.

The IBM 300PL uses a screwless case design which causes it to suffer similarly to others 90’s screwless cases. The plastic has become brittle with age and is easy to accidentally snap off making shipping and even routine case open and closings a risky endeavor.

ibm300pl4

Above are the internals along with a view of where the drives are oriented. One interesting thing about this motherboard that you can’t see to well in this image is that floppy, IDE and power connectors are all located on the riser card rather then the motherboard itself.

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With the removal of two screws the 5 1/4 bays can fold up on a hing allowing easy access and revealing a bay on the underside for a hard drive. I like this feature as it makes swapping drives very easy.

The primary IDE connector is actually located on the side of the riser card facing 5 1/4 bays. The primary power connector is also located on this side which can be made out in the background.

ibm300pl7Now to take a look at the riser card itself.

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Here you can see the secondary IDE connector as well as the floppy connector and power connector for the floppy drive, which is somewhat odd seeing as power is not being supplied by a cable straight off the power supply. This riser card has three PCI and two 16-bit ISA slots though one of the PCI/ISA slots is shared. This is more then adequate for a late DOS or early windows rig in my opinion

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1) CPU – The 300PL is an early socket 7 motherboard with the Triton II chipset which seems to have been a high-end offering at the time. My 300PL came with a Intel Pentium 200mhz installed but I upgraded it to a 233mhz MMX CPU which is officially the fastest CPU it can take. Upgrading the CPU is possible though with something like a PowerLeap PL-K6-III. The stock CPU does not come with a fan on the heatsink but the case fan is located directly below the CPU blowing air over the heatsink.

The 300PL has 512kb of on-board L2 cache which I suspect are the two chips located just above the CPU

2) The 300PL is very picky about RAM. According to official documentation it must be EDO nonparity (NP) or EDO error correcting code (ECC) DRAMs of up to 128mb in size. Mine currently has 128MB that came installed when I acquired this machine. The max RAM that is physically possible to install is 384mb since there are only three sockets for RAM and the machine is only capable of using 128MB sticks each. The chipset itself though is capable of supporting 512mb of RAM. I attempted to use various RAM sticks over 128mb and none were accepted.

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3) Video – The built in video chip is actually rather good and is the Matrox Mystique 1064SG-H chip. Not a surprising choice seeing as this machine has business uses in mind but it still makes a fast chip for DOS games and offers excellent 2d image quality as well as providing some early 3D abilities. The Mystique does have some compatibility issues with things like fog layers in some games but overall is a good chip, especially when paired with something like a Voodoo 1 or 2. The chip comes with 2mb of video SGRAM built into the board with the option to increase the amount to 4mb with an add on card. There is also connections for video option cards like the Rainbow Runner.

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That white connector to the right is for an optional IR upgrade.

4) Switch block – Rather then use all jumpers to make settings IBM opted to use a nice switch block to help set things such as CPU speed. Here is a shot of the info sheet on what the switches control located on the underside of my case.

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ibm300pl13(double click to enlarge)

5) CMOS Battery – Next to the switch block is also located the CMOS battery for saving changes made in the BIOS.

That’s about it for the IBM 300PL type 6562. It’s actually not a bad choice for a DOS machine or early Windows. The amount of options built in is nice and the the built in video is actually very good for the time especially when paired with a Voodoo card. The case, although very estheticly pleasing, at least to me, suffers from aging brittle plastic issues as do most screwless 90’s computers.

A great resource on the 300PL 6562 HERE

Benchmarks (Intel 233mhz MMX, 512kn L2 cache, 128 EDO RAM, Built-in Matrox Mystique 1064SG-H)

3D Bench – 163.6

PCP Bench – 58.1

DOOM – 82.7

Quake – 45.6

Speedsys – 175.43

IBM PS/2 Model 30 286

Last month I did a article on the IBM Model 55sx, A machine I myself was not to crazy about. It was certainly functional but hampered by so many little things and a few big things as well such as the proprietary MCA expansion ports. This time I’m going to talk about the Model 30 286 also of the IBM PS/2 line. This machine seems to have become one of the more desirable PS/2’s most likely because this machine unlike many others of the line is actually equipped with standard 16 bit ISA slots. will this be enough to redeem the system or will it be dragged down by the little issues that plagued the 55sx? Lets read on and find out.

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The case is virtually identical to the previous 55sx and again it’s a nice small desktop case. Again there is not much room for expansion and your basically limited to a standard floppy drive, hard drive combo or two floppy drives.

ps2302863Taking a look at the back.

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Not a whole lot to say since the back is very much like the 55sx though arranged a little different. The VGA port is mid case and before the other ports. The port is indeed VGA and not MCGA as on the 8086 based model 30. The port on my machine did not work but I’m unsure of the reason. perhaps a dead video chip. Below and to the right are two ps/2 ports for keyboard and mouse. Following that is a larger serial port and a parallel port.

I won’t go over the two cards I installed but they are a Trident 8900 VGA card and a early 16-bit Sound Blaster 16 sound card. The sound card is a bit “noisy” but its setup by jumpers which is important seeing as this is a 286 based machine and the plug and play setup program requires a 386.

The floppy drive is a 1.44mb drive but like most of the ps/2 line it is proprietary so you need a floppy drive just for the ps/2. also like the 55sx it uses a sled that the drive sits on to install into the bay.

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The hard drive is also the same ESDI style drive that was in the 55sx with the same style connector. Mine is what appears to be the original 20mb drive and it still boots up just fine.

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The first thing you can tell right off on opening the case is that the model 30 286 is one of the few ps/2 models that use the 16 bit ISA expansion slots as opposed to MCA. This was because at the time this was considered the cheaper budget version but as time saw the MCA format die off this model and its slower 16 ISA has remained far more versatile and useful as a retro computer.

1) Power supply & switch – This machine again uses the common power arrangement found in the IBM PS/2 line of having a mechanical switch connected to the front that via a hooked rod physically powers on the PSU on power up. A little strange overall but from researching and comments this actually turns out to be a safer method then directly connecting the power to a front switch as is the common practice.

2) CPU – The Model 30 286 as the name would imply uses a 10mhz 286 CPU. The 10mhz 286 is one of the earlier and slower 286 CPUs and in my opinion for this machine is in a rather awkward place. I say that because it feels a little to fast for some CGA games that require a 4.77 8088 or V20 to play at correct speeds. At the same time the 286/10 is a bit to under powered for the bulk of the later VGA games and lacks the “coolness” factor of a NEC v30 machine that’s for the most part running at the same speed. It should run many slower paced games from the late 80’s and maybe even early 90’s in EGA fine though.

ps2302868I’m not sure the reason for that yellow wiring above the CPU chip or if that’s factory done.

This CPU crystal oscillator is soldered onto the board.  You could in theory desolder everything and resolder on a faster oscillator and add a faster chip but it’s unknown if this will work or be stable. There are A few official CPU upgrade “snap” on upgrades though such as the HyperACE SX (M30) as well as a few others do exist. I’m not sure though if these upgrade chips will work with other machines or if they are specific to the model 30 286.

486slc2486SLC2 50mhz 486 cpu upgrade (image courtesy of user Nestor at at the vintage-computer.com forums)

IMG_20140407_114755_540 HyperACE SX (M30) 386-25mhz CPU upgrade w/ math copro / 64k SRAM cache (image courtesy of user lowen at the vintage-computer.com forums)

3) co-pro socket – This is a socket for a 287 math coprocessor to assist with complex mathematical computation. Mine as you can see lies empty. Not terribly useful unless your doing CAD applications or running one of the few games like SimCity that take advantage.

4) CMOS Battery – Again we have the infamous Dallas RTC battery. Mine seems to be the later revision but unfortunately it still appears to be either incompatible or dead. I’ll repeat here what I wrote in my model 55sx article “The Dallas RTC is basically a lithium battery coated in a hard plastic shell and then socketed into the board. The problem is these chips and even their updated and more recently manufactured replacements are out of production. Throw in the fact that many of these are now dead, the newer replacements aren’t guaranteed to work the same and that the system will act erratically, throw errors (error 161) on boot or not work at all without a working battery and you have a major issue. The best fix for this issue is hacking the battery to use a modern coin form lithium battery externally. Instructions on this process can be found here as I have not attempted it yet. Ive read and seen some videos where the newer replacement battery the Dallas DS12887 works fine but other sources indicate issues such as a clearing of the CMOS after restarting.”

It is worth saying that my machine seems to be able to boot up to its hard drive regardless of the CMOS battery being dead and without the need for a reference disk. After the error codes if you wait a few seconds an image will appear and if you hold down the F1 key the machine will continue to boot up.

5) Speaker – The speaker on the 30/286 is a cheaper Piezo beeper speaker which makes sense seeing as this was considered a budget machine.

6) RAM – My machine has 1MB of RAM installed but the max capable is 4MB. unfortunately the PS/2 30/286 does not take standard 30 pin RAM but instead uses proprietary “PS/2 Type” RAM which can be a little hard to find. Some of the IBM RAM sticks use sort of odd looking metallic box memory chips as you can kind of see in the image below.

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So is the PS/2 model 30 286 a good retro machine? Well…not really, at least compared to other OEM or self built setups. Again in my opinion it’s from the hassle involved. The proprietary RAM, the proprietary floppy/hard drive interface and Dallas RTC battery and even still the reference disk even if its not as big of a deal. Is it far better as a retro PC then the “high end” MCA PS/2s? Yes, and if you are a IBM fan and want a PS/2 then I would suggest this machine. Many of the above issues of the other models are mitigated by the use of standard 16 bit ISA slots in this machine. The hard drive can theoretically be replaced with something larger and newer via a cheap and available ISA IDE or SCSI controller. The problem with doing this is that there are NO molex power connectors on the PSU to power a hard drive or floppy drive. I am unsure if a standard power supply will fit in its place but even if it did it was almost assuredly make the front power switch useless. Upgrading the sound and video is also much easier with the huge array of ISA video and sound cards now usable. Earlier sound cards that are jumper configurable are recommended though due to the none plug and play nature of the system. As I mentioned earlier the CPU for me holds kind of an odd place but if you don’t have any other better machines of the era this one should fill some of your needs.

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IBM PS/2 Model 55sx

The IBM PS/2 (or Personnel System 2) line, both greatly reviled and greatly beloved by….oh, well…actually mostly reviled. The IBM PS/2 line was a series of many computers mostly targeted for business use and containing many proprietary components in an effort to reverse the perceived damage and loss of revenue caused by the flooding of the market by “IBM clone” machines. This massive use of proprietary components is both why the PS/2 is hated but also beloved in a way that some of the additions such as the ubiquitous ps/2 ports that would come standard later on PC’s as well as the modular design introduced in many of the PS/2 line made opening up the machine easy. As game machines though most of the PS/2 machines fall flat and this can mainly be attributed to the MCA (MicroChannel Architecture) expansion slot introduced in the line, a faster then ISA but poorly supported bus slot.

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The machine I’ll be looking at here is the IBM PS/2 model 55sx, a prime example of the MCA PS/2 line and what IBM created as a low end to mid range model PS/2 for business and professional uses. I want to point out right away I never did get this machine fully working and in the end I had to cannibalize a few parts for a more useful ISA equipped PS/2 I’ll be covering later.

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The model 55sx was released around 1988 though Wikipedia states 1989 and the copyright date on the case is 1987. The build quality overall is very good and typical of IBM. the case is a desktop design and is pretty heavy though not very large. There is very little room for any expansion with two 3 1/2 slots really only suitable for a floppy drive or hard drive which was the typical combo setup as seen on this machine. The drives are on sleds much like in a desktop Macintosh’s of the mid 90’s. The power switch to the far right is an actual heavy duty switch and not a button as was typical on many cases and becoming more common. The floppy drive is a 1.44mb 3 1/2 floppy drive but the drive itself is proprietary to the PS/2 and uses a special connector.

ibm55sxflop

As you can see there is no separate molex connector for power and the power is supplied via the floppy cable connector. This connector is not IDE though it looks like it. PS/2 floppy drives typically feature a large blue eject button on the front sometimes with the disk format on the button.

I believe the hard drive in mine was a standard 30mb drive that came stock. The hard drive is of ESDI format which is different from IDE or SCSI and from what I understand fairly fast for the time and comparable to SCSI though it quickly faded away as the 90’s approached.

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These drives like the floppy also lacked a separate molex connector as power was supplied via the edge connector.

Now lets take a look at the rear of this machine.

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The rear ports consist of two ps/2 ports for keyboard and mouse. The introduction of the ps/2 ports which get their name from the PC line are perhaps one of the best new features introduced with the IBM PS/2 line and one of the most influential on future PC design in the coming decade. Next to that you have standard parallel a DB-25 serial port and finally a standard VGA port that the PS/2 line was helping to standardize and promote at the time. The introduction of the VGA standard is possibly the greatest legacy of the PS/2 line with ps/2 ports right behind. Expansion is fairly weak with only three slots available via a riser though being that this is a MCA based machine the point is largely moot for gaming anyways, which is something I’ll discuss as we delve deeper into the machine.

There are also two punch out holes above the ps/2 ports in case you want to chain the machine to a desk so your untrustworthy employees don’t take it home with them or to thwart looters that forgot their chain cutters at home.

The case opens by removing a few screws on the left and right sides. On lifting the top half of the case away an interesting feature of the power switch becomes obvious.

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The switch on the front of the case is actually just a switch to flip a another switch operated by a hooked metal rod. Why this approach was taken rather then having it directly wired up I have no idea though I have read some material that suggests this sort of setup it actually safer as the power supply is truly off when the PC is powered down.

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1) CPU – The model 55sx sports a 386SX CPU at 16mhz. The processor is soldered to the motherboard so except for a possible rare and hard to come across MCA CPU upgrade cards your stuck with the 16mhz 386. The SX designates a 16 bit CPU. There is no math coprocessor built into the chip but luckily there is a socket for a 387 math co-pro next to the CPU. The 16mhz 386 itself actually isn’t a terrible chip even though it’s a lower end to mid range 386 it still has enough power to play a wide range of early 90’s DOS VGA games, applications and even Windows 3.1 and below adequately if you want.

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2) Speaker – The 55sx does have a full PC speaker as opposed to a beeper speaker which is very nice as you will most likely be stuck with it as upgrading sound on a MCA machine can be expensive and difficult

3) RAM – This machines came with the 4mb maximum via 2x2mb sticks of RAM but can be expanded beyond this to either 8MB or 16mb via a RAM expansion card.  Information on maximum total supported RAM limits seem to be conflicting on researching the internet though it seems that limit is 8mb rather then the 16mb stated by some sources. The RAM is of the 72 pin variety which is something else the PS/2 line introduced to replace the old 30 pin standard but it may be proprietary “PS/2” type RAM rather then standard 72 pin though I cant seem to find any concrete confirmation of this nor did I have the will to swap out modules for testing. The 55sx requires 80ns modules and will not accept faster 70ns without modification

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4) RTC battery – This is the infamous Dallas DS1287 real time clock and a source of unending frustration with PS/2 users. The Dallas RTC is basically a lithium battery coated in a hard plastic shell and then socketed into the board. The problem is these chips and even their updated and more recently manufactured replacements are out of production. Throw in the fact that many of these are now dead, the newer replacements aren’t guaranteed to work the same and that the system will act erratically, throw errors (error 161) on boot or not work at all without a working battery and you have a major issue. The best fix for this issue is hacking the battery to use a modern coin form lithium battery externally. Instructions on this process can be found here as I have not attempted it yet. Ive read and seen some videos where the newer replacement battery the Dallas DS12887 works fine but other sources indicate issues such as a clearing of the CMOS after restarting.

I also feel I need to point out that the 55sx does not handle hardware changes like most other PC’s via BIOS the same. The 55sx and most if not all of the PS/2 line require a “reference disk” to be inserted on making any changes such as replacing the battery. Thankfully these disks are not very difficult to find via the internet. This site has a link to the model 55sx reference disk.

5) MCA slots – This perhaps even more so then the Dallas battery is the bane of the model 55sx and many PS/2 machines. These are the MicroChannel Architecture slots which were designed to replace ISA.

ibm55sx6So much animal hair inside this system

MCA was faster then ISA (10mhz compared to 8mhz) had an increased data width as well as having limited “plug and play” capabilities but unfortunately the PnP capabilities required constant updates of the reference disk for newer cards. A lesser pointed out positive of MCA cards is they tend to have less interference or “noise” so an MCA sound blaster sound card should technically sound a little clearer then its ISA counterpart as well as video cards looking a little better then A ISA counterpart. In reality though most users didn’t seem to notice or care. MCA was not backwards compatible with ISA and IBM required a hefty royalty for its use in other manufacturers machines. For these reasons it never caught on and PC clone manufacturers ended up coming up with the EISA slot to counter MCA.

This riser has two different forms of MCA slots. The top two are 16 bit and the larger bottom slot is I believe a 16 bit slot with a axillary video connection. I’m guessing this is a special slot of some video cards but there is very little information I could find on it. I originally thought it may be a 32 bit slot but specification sheets for the 55sx claim three 16 bit slots and a German Wiki image reports the slot to be axillary video. The biggest issue with MCA cards are the lack of options as not to many third party manufacturers made MCA cards though SCSI, network cards and memory expansion MCA cards don’t seem to rare or expensive on places like Ebay. Video cards tend to be fairly generic and confusing as to the standard they support and specifications they hold. Sound cards are extremely rare and can be very expensive. This is the biggest issue for gamers with a PS/2 system. Companies like Creative did make MCA versions of the Sound Blaster 16 as well as a few other third party makers but these cards are very hard to find and pricy making any sound option other then PC speaker on a MCA system not very practical. IBM did make a somewhat easier to find and cheaper M-ACPA/A sound card but this card IS NOT SB16 compatible and games tend to sound very “off” and incorrect.

The connector on the top of the riser is actually to the ESDI hard drive as it interfaces via the riser card.

IBM VGA PS/2 monitors of the time are generally of good quality though the one that came with my model 55sx was sadly dead.

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 ibmmon2

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So my overall thoughts on the model 55sx and indeed most of the MCA PS/2 line? Don’t bother with it. If you like to mess around with old PC’s with unusual components go ahead if you can find one cheap and under $25 or so but overall and especially as a game machine the 55sx and all IBM PS/2 MCA machines do not cut it. The modular design and revolutionary changes it brought to the PC world such as VGA and ps/2 ports for keyboards and mouse were great for PC in general but better implemented on generic machines. The proprietary components are a hassle, The Dallas real time clock is a hassle, the MCA slots are a hassle, the lack of accessible sound options is a hassle and the reference disks are a hassle. Your far better off with a generic system with ISA slots even if you lose the ps/2 ports. One thing to look for though is the model M keyboard that came with many ps/2’s as it is a very good quality and many times worth more then the PC so keep an eye out if you can get one of those with a deal.

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