I can't give you an example (would that I could, I might have one myself). I can only make a suggestion as to a few places to look.

1) If you're flexible on layout, look to portable mid-80s machines (luggables) or dedicated word processors (though most of those are Z80 or clones).

2) Another place to look would be the last of the XT clones in the late 80s and early 90s. Again if I knew where to find them I would have one. They tended to be thrown out early and not kept in an attic for decades like higher-end machines, or upgraded sooner.

There were a couple of manufacturers who made "slimline" XTs and 286s around 1990, in smaller cases.

Didn't Vtech also make Z80/808x PCs before they became a cheap toy company ?

I've seen a few tiny XT motherboards here. Just click on "Photo" in each table.

Sergey's Micro 8088. cpu, fpu, 1mb ram, ps2 keyboard.

I have this board: https://stason.org/TULARC/pc/motherboards/H/H … 88-HED-918.html

The size is similar to those later 386 or 486 motherboards.

Mut wrote:

I have this board: https://stason.org/TULARC/pc/motherboards/H/H … 88-HED-918.html

How can it have 5 pieces of 4-bit RAM chips? 😲

BloodyCactus wrote:

Sergey's Micro 8088. cpu, fpu, 1mb ram, ps2 keyboard. […]
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Sergey's Micro 8088. cpu, fpu, 1mb ram, ps2 keyboard.

i've seen a few people building similar homemade 8088 boards, but obviously they don't meet my conditions above.

BloodyCactus wrote:

Sergey's Micro 8088. cpu, fpu, 1mb ram, ps2 keyboard.

By the same guy, there's also this:

http://www.malinov.com/Home/sergeys-projects/ … -88-motherboard

...which would pretty much fit the OP's requirements, if you got hold of an Intel Wildcard 88 module... and that's a big if 😊

Merovign wrote:

2) Another place to look would be the last of the XT clones in the late 80s and early 90s.

I'll have to agree with this. The following is a last-of-the-XTs clone by Hyundai. If the ruler doesn't make it obvious, its width is less than that of a cd case. It has ISA slots, serial, parallel, and a floppy controller. OK this is not exactly what you asked for with, although normal for its time, only 640KB of RAM (what for the extra RAM anyway, realistically speaking?) but I don't think any standalone m/b can get much smaller than this.

This NEC V20 board I gave to a Vogons member is fairly small. It was missing the keyboard din, but fairly easy to solder a new one on.

...and it looks like this Vogons member also grabbed the same model mobo back in 2011, but it had the keyboard din.

Re: Bought these (retro) hardware today

...but I have a tiny late XT clone too:

Yes, more memory anomaly here: it has 768kB of RAM (+parity) but of course only 640kB is visible.

With CGA you can get 768Kb conventional RAM for sure.

It would be a nice thing to make a MicroATX XT Mainboard with Trident VGA, HD Floppy Controller and IDE CF Socket,
and maybe Adlib Sound ? 😁

I also have a Faraday Clone based Board which is ultra small but its also very cheap made.
This means almost no deblocking on isa slots and so on..

matze79 wrote:

With CGA you can get 768Kb conventional RAM for sure..

True. As fas i do remember, the usual steps are (or rather were) 704K/736K/768K. 😀

The 704-736K region is used by the MDA's text mode, afaik.
"This address is not completely decoded; the entire 32k from 0B0000h to 0B7FFFh is filled with repeats of this 4k area."
Source: https://www.seasip.info/VintagePC/mda.html

(Hercules' graphis mode, by contrast, is nearby to CGA's; in half-mode, both can co-exist.)

Afaik, OS/2 even had a special "CGA" mode option for its DOS VMs,
providing 736KB of DOS RAM (OS/2 itself was running on any card's mode, like VGA).

Here's a quick video wth a 704K setting, which leaves CGA and MDA/Hercules modes intact. ^^
https://youtu.be/8nMB8XvwUJo

Edit: Picture added.

Given the fact it has VGA, LAN and serial ports, I'd call it pretty compact. Sadly, only 256KB RAM.

alvaro84 wrote:

...but I have a tiny late XT clone too: […]
Show full quote

...but I have a tiny late XT clone too:

Yes, more memory anomaly here: it has 768kB of RAM (+parity) but of course only 640kB is visible.

Forget about the 768KiB: that board has a SIPP socket!

matze79 wrote:

It would be a nice thing to make a MicroATX XT Mainboard with Trident VGA, HD Floppy Controller and IDE CF Socket,
and maybe Adlib Sound ? 😁

I think I'd prefer an integrated MPU401 to an integrated Adlib. Also clock speed controls like the Micro/Xi 8088 would be ideal. Designing for an 8086 would be extra interesting since it never seemed like a popular processor outside of the value end of the PS/2 line and it'd be very neat to run the chip that named the x86 family. I figure that'd make design a lot more complex though, especially since there'd likely be substantially fewer chipsets/designs to support it.

Error 0x7CF wrote:

matze79 wrote:

It would be a nice thing to make a MicroATX XT Mainboard with Trident VGA, HD Floppy Controller and IDE CF Socket,
and maybe Adlib Sound ? 😁

I think I'd prefer an integrated MPU401 to an integrated Adlib.

I'd be happy with a simple game port already. Can't believe it is still somewhat being neglected by clone makers (it was an original IBM product!). 😢

Forget about the 768KiB: that board has a SIPP socket!

I've never even dared to try 🤣 Mostly because I couldn't see the point. Even the DIPs are too much 😁

(I'm not even sure it's really a SIPP socket. Maybe. Probably...?)

Yes, more memory anomaly here: it has 768kB of RAM (+parity) but of course only 640kB is visible.

If the system has a CGA or Hercules card installed, just add 704K.COM to autoexec.bat
It'll increase DOS RAM to 704K, at least. If RAM is available at the A segment block (if memory is contingous)..
The rest can be made accessible as UMBs, if it isn't overlapping with anything else.

alvaro84 wrote:

Mut wrote:

I have this board: https://stason.org/TULARC/pc/motherboards/H/H … 88-HED-918.html

How can it have 5 pieces of 4-bit RAM chips? 😲

It uses the 4 bit chips to do 8 bits. So a 44256 (4x256k) becomes 8x128k

For every memory read, do two read accesses
Set the most significant bit of the address to 1 (the rest of the address bits are connected to the CPU)
Read the 4 bit value, and store it in a 4 bit latch
Set the most significant bit of the address to 0
Enable a buffer which has bits b0-b3 connected to the RAM, and bits b4-b8 connected to the latch.

For every memory write, do two write accesses
Set the most significant bit to 1, and use a multiplexer (e.g. 74LS157) to send data bits b4-b8 to the RAM, and send a write pulse to the RAM
Set the most significant bit to 0, and use the multiplexer (e.g. 74LS157) to send data bits b0-b3 to the RAM, and send a write pulse to the RAM.

In order for this to work, you either need fast memory, or a slow CPU.

You only need one lot of control circuitry regardless of the number of RAM devices.

The same technique was used on the Acorn Electron which used a single 4464 (64kx4) device to provide 32kBytes of RAM. (https://en.wikipedia.org/wiki/Acorn_Electron)
The 6502 ran at 2MHz when executing from ROM, but ran at 1MHz when accessing RAM. The RAM was accessed at a rate of 2MHz, but every byte required two accesses.