Hardware pickups

Recently I’ve been able to pick up some interesting hardware and I thought I’d share some photos of it with you. It was also an opportunity to try out some better lighting in the hope of getting better pictures.

387sx 33MhzThis unfortunately wasn’t the greatest photo due to the reflectivity of the packaging.

First up is a pair of 80387sx co-processors from the mid 80’s. Very few people actually bought and installed these chips as floating point arithmetic was mostly only used in scientific applications or Computer Aided Design. Consequently chips like these can be quite rare, and this pair clock in a 33Mhz making them some of the faster 387’s.

Intel weren’t the only company making co-processors for the 386, these included Cyrix, Chips and Technologies,  IIT, ULSI and Weitek. Most of these were faster than the Intel part, but had some compatibility issues, and some were of completely different designs.

Interestingly the NPU’s as they were known could be clocked asynchronously from the CPU. They also could operate whilst the CPU was busy doing something else, which gave machines with these some very crude parallel capabilities.

Here we have a Sun Microsystems mainboard from a Sparcstation IPX. The machine came in a neat lunchbox form-factor that was actually impressively small. This particular board has a Weitek Sparc processor that ran about 40Mhz. These chips had an FPU on-die, so they would have been similar to the 486 in performance. The LSI chip and some of it’s supporting chips are likely the 1Mb of system cache which was quite large for the time. The Sun GX chip is a graphics controller which contained some basic drawing acceleration. These features made the IPX quite an impressive little workstation. Most of the chips and the board itself appear to be manufactured in 1993.

It’s a shame I don’t have the rest of the machine, I’d like to be able to run this little beast. I’m not even sure I can get RAM for it, or if what I have is compatible. I’ll have to keep an eye out for the chassis and other parts.

Mechanical Keyboard

Mechanical Keyboard

This might look like an ordinary keyboard, but it is a proper mechanical switch keyboard that came with the next piece of hardware (a PC clone). Despite its very plain looks it feels fantastic to type on and has that distinctive mechanical sound. It has a larger DIN plug which actually suites many machines up to and included many Pentium based machines. It is a bit grubby but in otherwise good condition.


Lastly we have an interesting PC clone. This one was made by a company called Microbyte, which turns out that they were an Australian company based in Adelaide who made PC clones such as this one. It is clear that they designed and built their own boards and wrote their own PC compatible BIOS. Quite an achievement for what must have been a small engineering company. I found very little information about them online unfortunately.

My machine is a PC230sx, which has a 386sx@20Mhz with a Trident VGA card. It has SIPP memory fitted for both the main memory and video memory. They installed an unusually large amount for the VGA, having a full 1Mb of video memory. The system RAM is 2Mb in total.

When I bought this machine I didn’t think it had a hard disk, but it turns out that it has a Seagate ST3144A which is 130Mb. Probably an impressive and expensive drive in it’s day. This drive still works, I just had to configure the CMOS with the drives details which are handily written all over the machine.

You may notice the socket for a WD33c93 chip, this was a SCSI controller chip. This would have to be one of the few older machines that have the capability of on-board SCSI. I’m not sure why the chip is missing here, but these machines were apparently commonly fitted with SCSI drives instead. Looking in the BIOS seems to indicate that they were supported for booting. I may have to find one of these chips and see if I can get SCSI to work.

Between the VGA chip and VLSI chips lays an extremely long header where the expansion riser card would normally be inserted. This machine doesn’t have the riser card, so I can’t plug in a sound card or anything else which is a bit of a shame. I’m surprised the machine works without it as I’ve seen many other machines which don’t work correctly or at all when it is missing.

This board has some stickers that look like they were written by a service technician, they are attached to a part of the board under the floppy drive where there is a blank area containing no visible traces or chips. The first sticker reports an invalid opcode at a particular memory address which could indicate a problem with RAM or software.

Fortunately after testing the machine I’ve found the only problem so far is the malfunctioning COM1, the rest of the machine appears to be functional, and the IDE hard drive boots DOS ok. I have noticed that the Floppy drive light stays on, something which sometimes indicated incorrect installation of the cable. In this case the cable is correct, and the drive even reads disks, so there is likely a jumper setting on the drive that needs correcting.

I benchmarked this machine with Topbench to see how it compares to others. It was marginally faster than a 286@16Mhz with a 287 co-processor. I think there may be a few factors that contribute to this. Firstly I think the RAM must be a similar speed to that in the 286, thus slowing down the memory and opcode tests. It does perform better in the 3d games test which I found interesting as that has some floating point arithmetic. Luckily this is perfect for testing my homebrew platform game.

Finally I’m pleased with how the extra lighting has improved the pictures, but my technique still needs work. Perhaps another source of lighting is called for, or perhaps finally a step up to a better camera.


3 Responses to “Hardware pickups”

  1. February 20, 2015 at 3:56 am

    Nice finds. I’d love to have a 486 with that small form factor. cool PC with the exception of the built in Trident card. I never much liked Trident, probably because my fist Windows PC had a trident built in and it gave me lots of issues. the 8900 isn’t a bad chip though. the D variant is actually very speedy in DOS. Test show it actually rivals chips like the ET4000, not sure about the B. I scored a box of old PC parts this weekend as well. One such thing is a bizarre motherboard with a 487 copro socket as well as a OPTi Local Bus port…at least I think thats what it is. haven’t managed to get it to boot yet or positively identify the board.

    • February 20, 2015 at 11:11 am

      This version of the trident chip seems to work ok so far. The video memory is probably more likely to be a speed bottle neck as it is 80ns which corresponds to a maximum speed of about 12.5Mhz. I think the system RAM is probably faster, but I’ll have to check that. I am contemplating trying out one of the 387 chips in this machine to see what it’s like.

      did that 486 board have a 486sx on it? The 486sx is the only one not having the FPU on-die. The silly thing about the 487 was it was a complete 486dx that simply disabled the 486sx when installed, also the 487 was expensive hence not many people upgraded. I did some reading about the 486sx and have heard that it didn’t have any disadvantage in software not using the FPU, so until that became common practise it was quite reasonable to go with the SX.


      • February 20, 2015 at 12:10 pm

        not installed. The box I bought it from had a 486sx 25mhz CPU in it though and I assume that goes with the board. there is one jumper on the board to choose either a 486sx or DX so I’m assuming I can just put A DX in the main CPU socket and not have to deal with the 487 nonsense. If i can ever get it to post. it takes 30 pin SIMMs and I don’t have the right ones for it so I’m hoping that’s all I’ll need.

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