Any monitor with VGA will work, although the display will be stretched. Not sure how it is in the UK, but in the US, it'd be easier and cheaper to get a VGA monitor at a thrift shop than to get into converters.

Seems like a fairly generic, business oriented PC for that time. Probably ran DOS 6.x and Windows 3.1 (or Windows for Workgroups 3.11, think of it as 3.1SP2).

A CL-GD5422 is going to be connected via ISA (as opposed to local bus) which is slower, but is what any game from say, 1992, or earlier will target as it's all people had.

The RAM is installed as matching sets of four, and unlike dual-channel, it's mandatory. That all eight slots are filled means someone either spent a lot in 1993 or upgraded it later.

jakethompson1 wrote on 2025-03-29, 22:19:

Any monitor with VGA will work, although the display will be stretched. Not sure how it is in the UK, but in the US, it'd be eas […]
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Any monitor with VGA will work, although the display will be stretched. Not sure how it is in the UK, but in the US, it'd be easier and cheaper to get a VGA monitor at a thrift shop than to get into converters.

Seems like a fairly generic, business oriented PC for that time. Probably ran DOS 6.x and Windows 3.1 (or Windows for Workgroups 3.11, think of it as 3.1SP2).

A CL-GD5422 is going to be connected via ISA (as opposed to local bus) which is slower, but is what any game from say, 1992, or earlier will target as it's all people had.

The RAM is installed as matching sets of four, and unlike dual-channel, it's mandatory. That all eight slots are filled means someone either spent a lot in 1993 or upgraded it later.

Thanks for the reply

Its good to know that any VGA monitor will work. I have a widescreen that hopefully will work but will look out for something in the local charity shops and car boot sales.

As for the original use for the pc it was hooked upto a CMM in an engineering company and was still in use till last year.

Thay said they replaced the PSU recently which is nice.

Nice ! Found a few references but not much info. Can you take a few more pictures of the motherboard and the computer case ?

That looks like a fairly generic OEM desktop system with LPX form factor.

The onboard VGA is a Cirrus Logic GD5422, with 4 256k x 4 memory chips, giving you a total of 512kB. There are sockets for four more, which would definitely be recommended if you wanted to use this system with any kind of desktop GUI OS - with 512kB your max is 640x480 at 256 colours. Upgrade to 1MB and you can do 800x600 at 64k colours. For DOS gaming it is unlikely to make much of a difference - there are few games that would run on a 486-25 that need more than basic SVGA.

Given we can't find clear info, a good photograph of the whole motherboard (with riser&cards removed) would help get an overview.

dionb wrote on 2025-03-30, 19:19:

That looks like a fairly generic OEM desktop system with LPX form factor.

The onboard VGA is a Cirrus Logic GD5422, with 4 256k x 4 memory chips, giving you a total of 512kB. There are sockets for four more, which would definitely be recommended if you wanted to use this system with any kind of desktop GUI OS - with 512kB your max is 640x480 at 256 colours. Upgrade to 1MB and you can do 800x600 at 64k colours. For DOS gaming it is unlikely to make much of a difference - there are few games that would run on a 486-25 that need more than basic SVGA.

Given we can't find clear info, a good photograph of the whole motherboard (with riser&cards removed) would help get an overview.

Cheers

I plugged it in and booted into dos today, no windows but also no error messages 😀 . I will give it a good clean and take some more photos soon. Also i just bought dos 6.22 so will give it a fresh install.

As for upgrades i will probably install s sound card first and then look into the vga memory. What sort of chip should I look for in a google search?

Horun wrote on 2025-03-30, 15:45:

Nice ! Found a few references but not much info. Can you take a few more pictures of the motherboard and the computer case ?

Will take some photos soon 😀

I would look for GM71C4256A 70nS or equal, like M514256A, mb81c4256a or HY534256 in 20pin DIP. You might be able to use 60nS or maybe even 80nS .
If you lived in USA i could mail you some 80nS equals to try for free (have a few tubes of them)....

For monitors I had good luck with https://www.freecycle.org both CRT and more modern 5:4 screens, but you do have to wait.

Now that you know the PC works agree the sound card is probably the most important upgrade.
For what I assume will mainly be a gaming PC you don't really need windows, but it can be fun to use just for nostalgia.

Also waiting on the pics but would be cool if you told us ram and hard drive size as well 😀

Horun wrote on 2025-03-30, 21:49:

I would look for GM71C4256A 70nS or equal, like M514256A, mb81c4256a or HY534256 in 20pin DIP. You might be able to use 60nS or maybe even 80nS .
If you lived in USA i could mail you some 80nS equals to try for free (have a few tubes of them)....

Thanks for that. It looks like i can get some GM71C4256A off ebay for a small fee. I will probably do that.

Was going to say, you're lucky, it's socketed.... then I looked at the prices of 486DX and DX2 - The socket style suggests that it will be a 5V only, so that rules out DX4 (except the ODPR version) and other 3V models, depends what you want to do with it, if the difference between SX25 and DX2-66 would mean the difference between running things and not

Daniel4200 wrote on 2025-03-31, 06:06:

Horun wrote on 2025-03-30, 21:49:

I would look for GM71C4256A 70nS or equal, like M514256A, mb81c4256a or HY534256 in 20pin DIP. You might be able to use 60nS or maybe even 80nS .
If you lived in USA i could mail you some 80nS equals to try for free (have a few tubes of them)....

Thanks for that. It looks like i can get some GM71C4256A off ebay for a small fee. I will probably do that.

Here are a few photos

Daniel4200 wrote on 2025-03-31, 18:51:

Daniel4200 wrote on 2025-03-31, 06:06:

Horun wrote on 2025-03-30, 21:49:

I would look for GM71C4256A 70nS or equal, like M514256A, mb81c4256a or HY534256 in 20pin DIP. You might be able to use 60nS or maybe even 80nS .
If you lived in USA i could mail you some 80nS equals to try for free (have a few tubes of them)....

Thanks for that. It looks like i can get some GM71C4256A off ebay for a small fee. I will probably do that.

Here are a few photos

Daniel4200 wrote on 2025-03-31, 18:53:

Daniel4200 wrote on 2025-03-31, 18:51:

Daniel4200 wrote on 2025-03-31, 06:06:

Thanks for that. It looks like i can get some GM71C4256A off ebay for a small fee. I will probably do that.

Here are a few photos

Looks like you have the option of installing some cache memory down there in those 8+1 empty sockets.

Could be an option to give it a decent speed boost by adding those. Especially so if you decide to try upgrading the CPU at some point (most of the speed of a faster CPU will be negated to a large extent by the missing cache between the CPU and ram).

Not sure how much you are or will end up into DOS PCs, just a word of caution: before putting a lot of effort into upgrades, consider the likelihood that you end up with second, VLB or PCI 486, or a Pentium system before too long. You will run into a wall upgrading to this system wrt the video, as there's nothing you can do to upgrade from ISA to local bus.

What games were you hoping to play on this?
With the currant CPU think of it as a fast 386, or you could upgrade to a DX2/66 like Matth79 said which will allow you to play games like Doom.
Later dos games will want something faster than a 486, it really depends on how many retro PC's you want in total and which games interest you that'll decide where this fits in your lineup and how to best upgrade.
or
You might be like me and just like upgrading old PC's as much as possible, in which case this'll make for a nice mid range dos PC once all done

chinny22 wrote on 2025-04-01, 04:03:

What games were you hoping to play on this? With the currant CPU think of it as a fast 386, or you could upgrade to a DX2/66 lik […]
Show full quote

What games were you hoping to play on this?
With the currant CPU think of it as a fast 386, or you could upgrade to a DX2/66 like Matth79 said which will allow you to play games like Doom.
Later dos games will want something faster than a 486, it really depends on how many retro PC's you want in total and which games interest you that'll decide where this fits in your lineup and how to best upgrade.
or
You might be like me and just like upgrading old PC's as much as possible, in which case this'll make for a nice mid range dos PC once all done

I would like to get as much out of this as possible.

I have had a few other socket 7's with AMDk6cpu and a P2 in the past. This is probably the oldest "8086" loder than the one i had as a teen which was an AMD K5 75

As for games all I have on disk is a copy of Frontier elite2 so once i vave made a few upgrades i might lok at some new purchases.

megatron-uk wrote on 2025-03-31, 22:19:

Looks like you have the option of installing some cache memory down there in those 8+1 empty sockets.

Could be an option to give it a decent speed boost by adding those. Especially so if you decide to try upgrading the CPU at some point (most of the speed of a faster CPU will be negated to a large extent by the missing cache between the CPU and ram).

This is something i might look into.

installing cache will make a significant difference, it's kinda of important if you want to get the most out of the system