Pentium II Slim Tower

Last modified: Sun Oct 5 17:19:13 EDT 2008


← Dig it!  In a batch of old PCs that I salvaged, I found a slim tower PC from the Pentium II era!

...Or did I?


No, actually, it's an NLX desktop with the cover removed, turned up on its end.  Rather than being an early example of slim tower design, it's a late example of the now-universally-despised CRT-on-top "classic" PC design. ↓

It used to be you could get a stand to hold an NLX desktop in the sideways orientation to pretend that you had a tower.  However, the cover on this PC was already kind of broken, and if you put weight on one side the power button would quit working, so I just ditched the cover instead.  A ballpoint pen is needed to operate the power switch.


The problem with NLX PCs is—well, actually, there are many problems with NLX PCs.

  • Although the motherboard has an AGP slot, not just any AGP card will do.  It has to be an NLX AGP card, which fits around the back panel to utilize one of those runt slots in the case.
  • The ISA and PCI slots are on a riser card.  Standard ISA and PCI cards fit only approximately, which is to say, not really.
  • You get only four drive bays, one of which can't hold anything but a floppy drive without an extreme feat of cable routing.
  • There is not much room for round IDE cables.  Ribbon cables are threaded through narrow spaces around the load-bearing bulkhead in the middle of the case.


On the other hand, this was the most powerful PC in the lot that I salvaged.  The 450 MHz CPU with sSpec number SL2U7 is as fast as Pentium IIs get, and given enough memory it can run Windows XP quite comfortably.

With a TNT2 M64 PCI video card installed, it can almost play a DVD in Xine, but Xine pegs the CPU and drops frames.  Overclocking might have made it work, but the IBM BIOS doesn't support it.


The 440BX-chipset motherboard includes 4 MiB S3 Trio3D graphics on the AGP bus and Crystal CS4235 audio via ISA PnP, but no game port.  No game port?!?  This PC was intended for office use, so instead of a game port it came with a weird RFID attachment.

Unlike the PCI integrated sound that replaced it in newer motherboards, ISA Crystal audio works in DOS DOOM as long as the PnP configuration is done one way or another.  However, it's insufficiently SoundBlaster-like to fool Llamatron into running.  Interestingly, there is a real speaker in the front of the case that delivers credible sound if nothing is plugged into the output jack.


The PSU seems to have been carefully chosen or designed for just this computer.  The wattage is barely enough, there is exactly one power connector for each drive bay, and the wires just reach where they need to go.  I unborked the floppy drive, added a second hard drive, and switched the CD-ROM for a DVD-ROM with no power problems.  The biggest challenge was getting all the wires to reach.

Despite firmware updates all around, the IBM BIOS is finicky about booting from the optical drive.  Putting Smart BootManager on a boot floppy is an effective workaround, albeit with an excess of other features that aren't helpful for this limited need.


So what else is worth doing?  According to IBM's always-excellent labelling, it looks like I could increase the memory to 384 MiB if I could score some compatible DIMMs.


And score I did.  On EBay, a lot of three 128 MiB PC-100 ECC DIMMs plus shipping cost me a mere $8.18.  These replaced the two 64 MiB non-ECC DIMMs that came as original equipment. ↓


That's about it for this one.  No punchline.  With the constraints that the NLX form factor imposes, this PC is good for running office apps but not for tinkering or gaming.  I'll be using it to test out XP applications and bloated Linux distros before deploying them for real.


...or maybe not.  It turns out there is one good thing about an NLX desktop:  While drive bays are scarce, there's plenty of room to stack loose drives on top.  To facilitate setting up two hard drives for an old 486 that could not boot a CD, I removed pin 20 from one of the IDE headers, cut out the plastic retaining clip for the ribbon cable, and persuaded a full-length round cable to fit into the space available.