Identification of old DOS ISA cards and motherboard

[Mattata]

Hey y'all. I just snagged an old DOS 486 tower from a tag sale. It looks like someone attempted to put this together themselves but it didn't get completed. There are a few parts in here that had no real identification of their model, or even branding. I know what they do, I was just wondering if anyone could help me figure out exactly what i'm working with here so I can see to it that I get the computer to work. The most important one to find out is probably the motherboard.

 

1) This whale of a thing

 

2) This case. If i know the model of this or the mobo, it'll help me figure out which pins on the mobo to connect all the case switches and lights to

 

3) This IDE controller card

 

4) a 25-pin and 15-pin port expansion card of sorts

 

5) A... fax/modem card? Idk, this is a tad before my time

 

Thank you in advance on helping me with my vintage endeavors  here are some pics of the stuff I could figure out myself, if anyone is intrigued:

 

*A Microsoft InPort/Bus Mouse port card

 

*A Diamond Speedstar VGA video card (? mb of ram)

 

*A Roland MPU-IPC-T

[Mope El Two]

It is an Opti motherboard, and there is no math co-processor on your unit ( 80487SX)   (that's right, they were separate chips in the 486 days).

I hated these things, everything was set with jumpers, and jumpers are a pain, I used to have a pair of tweezers to move those things (they were everywhere - mobos, hard drives, cd-drives . . .)

Try this link for a little info on the mobo.

 

Your video card looks like it has 8 Hynix 256k chips, so you have a 2MB video card.

2 3.5" drives, one 5.25" and a 120MB tape drive, pretty high end.

Maybe they were using it to produce MIDI music?

[mariushm]

45 minutes ago, Mattata said:

486 motherboard made by OPTi probably, probably the one linked above.

Uses EDO or FPM memory (too lazy to refresh myself and get it right ), but I remember you had to insert 4 sticks at a time in order to get 32bit or 64 bit wide bus to the cpu - it had to match the bus width otherwise it didn't work or you got low performance.

AT keyboard connector on top, 486SX cpu (without coprocessor) , that battery (dallas chip on right) is a potential point of failure - they often fail after 15-20 years and that one was made in 1991, week 23. At least it didn't leak.

Doesn't seem like anything special, lots of 32bit isa ports but that's pretty much it.

 

 

Eh it would be faster to just look up the pins on the motherboard ... see if there's some legend for the jumpers on the back, or look up the jumpers in the link given above. 

Power on button gets connected directly to AT psu... and be careful that's main voltage on the button.

 

 

3) ide and floppy disk controller card, may be tekram dc-600 - seems fancy with the extra memory, may be some kind of controller with RAID-0 and RAID-1 and caching support (some notes say up to 16 MB of cache ram, and it's believable for the tech in those days)

 

 

4)  SERIAL controller - lets you connect external modems, various fancy devices like serial mouse, trackballs, other things

 

 

5) plain 8 bit modem , probably 14.4kbps , something like that. usrobotics sportster (says on bracket and can google fcc id) - ~ 15$ on ebay  

 

 

self explanatory vvvv

 

*A Microsoft InPort/Bus Mouse port card

 

* video card, vga, probably 1 mb of ram - those are 1 mbit chips, 8 x 1mbit = 1 MB fast page ram, 70ns latency etc made by hyundai .. 256 is there because they're 256k x 4 bit chips, so 1 megabit in total in each chip.... 8 chips x 4 bit wide per chip = either 32bit bus between vga chip and ram, or 16 bit (and pairs of chips in parallel)

 

 

*A Roland MPU-IPC-T ... yeah, midi card...

 

[Mattata]

@Mope El Two @mariushm Thank you for the insight. Now I'm gonna have fun sticking all of this together, nothing aligns correctly. Motherboard is naturally crooked in the case so the cards don't line up with the back correctly, and the screws used on the drives aren't correct, so they stick out and allow the drives to slide around in the case. Also, no matter how much I read up on them, jumpers will always confuse me. Do either of you know of any basic reference guides that can help me understand how to stick this guy together without messing something up? I'm interested in using it for fun, but other than finding a "DOS for dummies" book somewhere, i'm kinda in the dark. 

[mariushm]

remove the plastic standoffs from the motherboard.

insert them in the screw holes in the case, if they're supposed to be screwed and they're not just "feet". Make sure there's metal standoffs where there were screws.

align the board .. basically make sure the AT connector (keyboard) is right above the round hole in the case, then insert screws and tighten the board - place screws diagonally and screw partially before moving to opposite screw, as you gradually tighten the screws the board will automatically center itself

 

Jumpers are simple... the reset and turbo are switches, the polarity doesn't matter, you can insert the cable from the case either direction into a jumper on the motherboard. Turbo is opposite what you think... default is running at high frequency, when turbo is on bios slows the pc (either by reducing frequency or sometimes disabling cache memory on motherboard to make programs slower)

power on leds, hdd activity leds those have polarity, but if you insert them the wrong way the leds should not burn out - modern leds can handle reverse voltage of 5v and the small currents supplied through those headers ... however leds in cases so old may not be as good. Point is if you put them the wrong way nothing bad would happen except a small risk of damaging the leds

 

It's natural to see it a bit more difficult because back then things weren't as standardized as they are now, they mb manufacturers didn't group the front panel connections (ps on , reset, hdd led, power on led , speaker etc) in one place, every maker placed them where they wanted.  The mb format was somewhat standardized, but cases had all kinds of quirks

 

[Mattata]

@mariushm Sounds simple enough. Thank you for all the help