Retro Business Rampage: The IBM PC300GL

I have an infatuation with the desktop form factor. I don’t know if it’s because the first several PC’s I had were desktops or if I just like the compact nature of them: the monitor sits nicely on top, everything’s neat and tidy.

By the mid 1990’s, towers seemed to be replacing desktops in the home. At all the dealers in our area, the only home desktops seemed to be several years old and underpowered compared to their tower brethren. I’m certainly not going to say that was a trend everywhere, but it was noticeable. In the business world, however, the desktop form factor continued to be the standard, likely for the above-referenced “neat and tidy” angle. Often, desktops had pass through power for monitors. One power cable, keyboard, mouse, and a phone line for the modem. Easy.

A few years off the expensive failure of the PS/2 line, and shortly after the follow-up ValuePoint, IBM was trying to claw its way back into the business market it had effectively abdicated to cheaper clones. I’ve covered the ValuePoint line before and I have fond feelings for it. They were simple, compact, and generally got the job done, though generally at a slower pace than their competitors. They also topped out at a 60Mhz Pentium during a time of rapid speed increases.

The IBM PC Series succeeded the ValuePoint. IBM was harkening back to the name that made them famous. In many ways, the PC Series was far more open and upgradeable than the machines that preceded it. In other ways, well…IBM is IBM. We’ll get to that shortly. Despite some issues, though, the PC Series was a rock solid line for business applications, equipped out of the gate with either OS/2 or Windows NT (switchable using the recovery CD that was included in the box).

Given the business focus, it’s unsurprising that Ethernet cards were more common than sound cards. You didn’t need sound to work on a spreadsheet. The machine may or may not come with a CD-ROM drive, with curved bezels adorning the front of the case if no option drive was selected. This design led to their motto at the time: “Reliable. Boring. Beige.”

I may have that wrong. Maybe reversed the order or something.

Anyway, given the business focus, what kind of performance can we get out of this as a retro gamer? Is this machine any good for some old-school DOS/Windows 95 gaming goodness? Let’s find out.

I have the power!

Wait. No. No, I didn’t.

When I got this machine, I bought what I thought was a working unit based on the pictures. At least, there was some output on the screen: the hard drive didn’t boot to Windows. Imagine my disappointment, then, when I pressed the power button and nothing happened. I popped it open to inspect the inside. It was a bit dusty, but there were no major areas of concern. At first glance, the power supply appeared to be a standard AT, with its P8/P9 connectors plugged into the motherboard.

No problem, says I. I can pop in an ATX supply with an adaptor and be on my way.

Not so fast, says IBM.

A longer look led to further disappointment. In addition to the P8/P9 connectors, there were two similar connectors that should have carried 3.3v (one to the board and one to the riser). Okay, a bit of a problem, but there’s 3.3v ready and waiting on an ATX supply. But what the hell were these other connectors? And why was the power switch so small?

As it turns out, this machine was a victim of its time: power management capability was being touted as the next big thing, soft power was a selling-feature. Because the ATX standard hadn’t yet been finalized, IBM came up with a proprietary solution. The AT-style supply should have pulled a power-on signal from the motherboard, enabled by a momentary switch on the case. This wasn’t going to be fun.

I ended up hacking together a wiring harness that fed the 3.3v rails and should have received the standby power/power on signals from the board. Alas, it didn’t quite work that way. Again, I figured it wouldn’t be a problem: I’d just replace the power switch with a latching one, shorting PS_ON to ground, and move on. Cue another issue: latching push buttons, by their very nature, are in two different positions depending on whether they’re on or off. If the switch was on, the button the front of the case couldn’t reach it. If I extended it, the case front wouldn’t fit.

In the end, I solved it by building a momentary to latching control board using a 555 timer:

When I replace an AT power supply with an ATX supply, I also make another modification: ATX supplies do not provide a -5v lead. This lead was used for certain ISA cards, notably a handful of sound cards (though not the card I chose for this build). Because of this, I built an inline -5v regulator to provide this line, feeding it through to the requisite connector on the AT power line:

Beyond that, there weren’t really any other issues regarding proprietary parts. The only other gripe I had is that all the case screws were flat head and evidently had been torqued into place by Robocop. Those had to go. With my power problems solved, it was time to dig into the rest of the machine.

Something Old, Something New

As mentioned, the previous owner acknowledged that the machine wouldn’t boot into Windows. Looking through the BIOS, I noticed the hard drive wasn’t even configured. An auto-detect routine later, the machine booted into Windows 95. And if I’m honest, I wish it hadn’t.

Immediately upon the desktop loading, I was greeted with a picture of a very 90’s looking woman in a skimpy bikini riding a motorcycle. On that alone, I assumed this PC must have been out in a warehouse somewhere. While I wasn’t going to keep anything on this drive, I decided to take a look around and see if I could determine when it was last booted. I saw that the last defrag was 22 years ago and that it was set up on a schedule, so entirely possible that it had been 22 years since someone actually used this machine day to day. Incredible that it had been sitting in this state since then.

I rebooted with a Windows boot floppy and attempted to format the drive and immediately encountered “Attempting to recover allocation unit”. This drive was nearly dead and needed replacing. There are several options for drive replacement on an old machine, of course. Historically, CompactFlash to IDE was popular, though CF cards are getting expensive. I also use SD to IDE adapters on a lot of builds. However, since I was planning on running Windows 95 on here, CF/SD cards weren’t likely to be reliable enough. I settled on a 60GB SSD (formatted down to 8.4GB, as that’s all the larger the BIOS could see) using a SATA to IDE adapter. It formatted and installed Windows without issue.

I should mention that this particular machine didn’t have a CD-ROM, so I popped in one of the new old-stock ones I had lying around. While it’s black and doesn’t match the case, it does still look appropriate. I also took the opportunity to clean the 3.5″ floppy (which seemed to be working well enough).

The other thing this machine lacked was a sound card. For a retro gaming machine, that wasn’t going to work. That said, I didn’t exactly want to drop an AWE32 or Gravis Ultrasound in here. It didn’t fit with the idea of it being a reclaimed business machine. I toyed with the idea of using an Ensoniq PCI card, but as I planned to sell this machine, I figured an ISA card would be a better value for the purchaser. I settled on a Vibra SB16.

I also removed the ISA dialup modem and added a PCI Ethernet card to make it easier to transfer files to the machine without burning CDs or breaking everything up onto floppies. While I could also probably just hook the SSD up to an adapter and copy things over that way, I wanted to get the machine fully assembled after all the time it had taken to retrofit the power supply. I didn’t want to have to dig the drive back out.

The last upgrade was replacing the worn out, rattling, grinding, whistling(?) stock case fan. Here again, IBM had chosen to use a proprietary fan plug. In this case, however, it was easy enough to use DuPont connectors wired up to the new model, a Noctua that was whisper quiet.

After a thorough cleaning, I got it all buttoned up and powered it on. To my great relief, it booted right up and was very quiet. On to the software and testing!

Spinning the Hits of 1985 to 1995

The completed specs on this machine are as follows:

  • Intel Pentium MMX 233Mhz
  • 64MB RAM
  • 8.4GB SDD
  • 32x CD-ROM drive
  • Soundblaster Vibra 16
  • 3com 10/100 network card
  • 1.44MB floppy
  • Cirrus Logic 5446 integrated graphics

Given the above, we’re targeting mid to late DOS era up through Windows 95 without 3D acceleration. The video card has excellent DOS compatibility and good performance under Windows, though again without 3D acceleration. That said, the games of the time are largely software rendered and the 233Mhz Pentium MMX is ideally suited to run them well.

As I mentioned earlier (you were paying attention, right?), I went with Windows 95 and its accompanying DOS environment. Rather than configuring the “Restart in DOS” options, I went with a customized boot menu (courtesy of PhilsComputerLab), allowing booting to Win95 or various different DOS options.

I tested a wide variety of DOS games, ranging from shmups and fighters to first person shooters, with a few platformers in the mix, as well. Overall, performance was very good.

I ended my DOS gaming tests with Quake (using the software renderer). This is the only DOS game I tested which uses a CD audio soundtrack instead of Soundblaster/AdLib. It’s such an immersive experience and it sounds great coming through the Vibra. Performance here was also good, averaging a very playable 38fps at default settings.

When it came time for testing in Windows, I had a hard time deciding what to play. Obviously, this machine will run any of the basic “entertainment pack” style games with no issue. The video card is DirectX compatible, though it’s no behemoth. I settled on a variety of favourites.

For the purposes of gauging performance, I ran through the Quake 2 benchmark. I don’t think benchmarks are the “end all, be all”, of course. My guiding question is always “does this play well?”. That said, it’s good to know where you stand in relation to other systems. On that front, the Quake 2 time demo (software renderer) gave me a score of around 18fps. That seems low, but when I played through the first unit/campaign, it felt responsive enough. I will say that Quake 2 is probably the upper limit of what I’d do on this machine without upgrading the graphics.

The Windows loader for Doom II worked well and performance was great, as expected. I also played through an hour or so of Sid Meier’s Alpha Centauri, which actually released in 1999 or so, I believe. It’s a fantastic turn-based strategy game, like Civ but in space. I had no issues at all and performance/sound quality were excellent.

Regarding sound quality, I’ll admit I’ve been somewhat spoiled by various Roland units and higher end sound cards. It was a bit of a blast from the past to go back to a standard SB16. That said, sound worked in the various games I’d tested and mostly sounded pretty decent. Anyone who grew up with an SB16 would not find anything amiss.

A Note about Cache

I retested all the FPS games after adding a 256KB Coast module to see if it made a difference. In short, it did. I gained about 3fps in each game. I don’t think that matters so much in the DOS games, but it might make a big difference when it was just “on the edge” in Windows.


Overall, I was very pleased with this unit, despite the hurdles I encountered bringing it into the 21st century. As far as a DOS gaming machine goes, this system is absolutely superb. The Pentium MMX 233 was the last in the line for Socket 7 Pentiums and it was a fantastic swan song. All of the DOS games ran great, except where the system was too fast. In that case, software solutions exist to slow it down (in addition to potentially disabling L1 cache).

Windows performance was likewise great, especially in period-accurate titles. While Quake 2 made it work a little, everything else ran without effort. Additionally, due to the fast CD-ROM and SSD, load times were very good, both for games and Windows itself. 64MB of RAM seems to be the sweet spot for this unit, as nothing I was running required more and I feel that anything that did would likely need more oomph in the video department.

The newly refurbished system runs cool, quiet, and without any fuss. You really can’t ask more from a retro PC. Would I recommend this system to someone looking to get into retro computing? ABSOLUTELY. Beyond that, I’d even say that someone that has a 486 on the low end and a P3 on the high end could benefit from such a machine to cover the glorious Windows 95 era of gaming. This system just “feels” so right for that OS and the Windows 95 boot sound never fails to inspire feelings of nostalgia. This is truly a prime example of mid-90’s IBM.

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