Regarding PSUs, you can get a simple adapter from ebay, so you can then choose any modern PSU you like. Regarding HDDs, you could use a compact flash card with an appropriate adapter. Ebay is awash with them.

Regarding a CD-ROM drive, I've tested a handful of DVD-ROM (reader) drives on 486 mobos, and nearly all of them worked. I regularly transfer files from my main Windows XP box to my retro test boards via one handy DVD-RW disc.

If you get a huge capacity HDD, you might find you need to limit its capacity so that the mobo's BIOS doesn't get confused. One utility that can do this is Seagate's SeaTools for DOS. It's a free download, and works with non Seagate HDDs.

I bought a modern ATX case for a retro build. It's amazing how much metal you can slice through with one of those cheap junior hacksaws! I had to do this to get some large old ISA soundcards inside.

But with a modern case will the holes for the motherboard mounting screws line up with the holes in the board or would that take more modding? I might be able to find some old cases in the basement at work though. Think I might use a modern hard drive and just limit it's capacity as you suggested.

Case? What for? 😁

🤣 @ h-a-l-9000!

So what are those adapters for modern PSU to old MB called? I will search for them on eBay.

h-a-l-9000 wrote:

Case? What for? 😁

Hehe!

rick12373 wrote:

So what are those adapters for modern PSU to old MB called? I will search for them on eBay.

Try searching for -

at atx power
or
at atx psu

Here's the cable you need. You will also need the correct ATX I/O shield.

http://cgi.ebay.com/ATX-to-AT-Motherboard-Pow … =item5882e626d2

http://store.thirtyday.com/atioshbaplal.html

I am under the impression that ATX and AT motherboards have mounting holes in common, though all of my cases are inwin, so I don't have much to compare against.

Another ebay search is -

at atx switch

One of the results returned (from pcpartsplusmore-store) shows the AT cable section having just the "P8 P9" plugs, as I don't think you need the 3rd white plug on the end. (I think that was for a specific Dell mobo, or something..)

Yeah, I guess if you buy the converter cable, make sure yours comes with a switch.

I found an ancient 386sx in the basement at work. I think the case will work for my 486 build. I just spent a few minutes removing the original parts from inside. They really made things solid back then! It has a huge 200 watt PSU in it. Before taking it apart I turned the thing on and it still worked. Maybe I will use this PSU until it dies.

Anyway, I like the retro look of the case!

So, anyway the biggest problem I might be facing is if the Dallas chip has last it's charge. I should be able to fire this board up tonight to see what happens. If it is has no charge what do you think my options are?

I just found a step-by-step guide to "hacking" in to the Dallas chip, in order to replace its internal battery -

http://www.instructables.com/id/Revive_a_pre_ … an_IBM_PS2_55SX_/

I don't know whether buying a new replacement Dallas chip (DS12887, not DS1287) on ebay is worth trying? Here's one -

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewIt … _fvi%3D1&_rdc=1

Saw and soldering iron...
And hot air if it is not socketed.

Others like to torture the poor RTC chip with a Dremel.

Wow, you found some invaluable info there. I looked through it real quick. Would just getting a replacement chip from eBay be easier? It should just be a case of popping the old one out and putting the new one in I would have thought.

rick12373 wrote:

Would just getting a replacement chip from eBay be easier? It should just be a case of popping the old one out and putting the new one in I would have thought.

Note to self - dig out one of your 486 Dallas boards, buy one of those new DS12887 chips, find out if they can be swapped, report back to Vogons. 😉 😀

Unfortunately, I've got a funny feeling that it's not guaranteed to work.

In that step by step guide to hacking the chip he says right at the end that if he were to do it again he would try drilling some holes in and soldering in some wires so that an external battery can be connected. He has marked on a picture where this should be done but without paying and registering the site will not let you see a big version of the picture. That is annoying as it sounds like it may be an easier way to fix it. I haven't tried firing the board up yet but will try tonight. I put it in the new, old case I found yesterday, put in the graphics card and put a heat sink and cooler on the CPU (had a brand new 486 heat sink and fan in a box that had never been opened). You don't have to use thermal grease for these old CPU's do you? I couldn't see any on the old heat sink I took off.

I have ordered one of those chips from eBay. If I use it and get it to work I will let you know.

How much RAM do you think I will need in this board? I think the max is 256mb. There are 4 slots. With this kind of RAM do you have to install the same size in pairs? It's been too long and I can't remember. Looking through my parts I have 4 16mb chips, so I can get it up to 64mb. For the software that a machine from this era will be running what was the max RAM that was needed?

I had a whole bunch of EDO ram and it is difficult to figure what size each chip is. A lot of it only had chips on one side. So does that mean they are likely to be really small and not worth bothering with? The 16mb ones I found have 8 chips on either side of the chip. I managed to verify their size by looking up the serial numbers on the net. Is it worth trying to find out what the others are if they only have chips on one side or have only 2 or 4 or 8 chips on them in total?

72-pin SIMM = 32 bit data width
Pentium -> 64 bit memory bus -> pairs
486 -> 32 bit -> no pairs required

Well the best I can find is 16mb chips. I have 4 which are the same make. Will 64mb be sufficient for a 486DX 100?