VOGONS


First post, by noshutdown

User metadata
Rank Oldbie
Rank
Oldbie

8088/8086 boards are usually supposed to be large with many discrete components and low-density 32kb ram chips, rather than integrated chipsets and simm slots. whats the most compact one you have seen?
this doesn't include industrial card-style boards, it should be in baby-at form with following features:
5~6 8bit isa slots(8086 should have 16bit isa slots)
highly integrated chipset
9*128kb ram chips or 1*simm slot(8086 requires 4*256kb simms)

Reply 1 of 27, by Merovign

User metadata
Rank Member
Rank
Member

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.

Reply 2 of 27, by Jo22

User metadata
Rank l33t++
Rank
l33t++

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.

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 3 of 27, by BloodyCactus

User metadata
Rank Oldbie
Rank
Oldbie

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

Micro_8088_Assembled_Board-1.1.jpg

--/\-[ Stu : Bloody Cactus :: http://kråketær.com :: http://mega-tokyo.com ]-/\--

Reply 4 of 27, by Mut

User metadata
Rank Newbie
Rank
Newbie

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.

Attachments

Reply 5 of 27, by alvaro84

User metadata
Rank Member
Rank
Member
Mut wrote:

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

Shame on us, doomed from the start
May God have mercy on our dirty little hearts

Reply 6 of 27, by noshutdown

User metadata
Rank Oldbie
Rank
Oldbie
BloodyCactus wrote:
Sergey's Micro 8088. cpu, fpu, 1mb ram, ps2 keyboard. […]
Show full quote

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

Micro_8088_Assembled_Board-1.1.jpg

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

Reply 7 of 27, by einr

User metadata
Rank Member
Rank
Member
BloodyCactus wrote:

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

By the same guy, there's also this:

wDWYjcu.jpg

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 😊

Reply 8 of 27, by konc

User metadata
Rank Oldbie
Rank
Oldbie
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.

IMG_20190412_234532.jpg
Filename
IMG_20190412_234532.jpg
File size
1.68 MiB
Views
731 views
File license
Fair use/fair dealing exception

Reply 9 of 27, by liqmat

User metadata
Rank l33t
Rank
l33t

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.

NEC_V20.jpg
Filename
NEC_V20.jpg
File size
1.79 MiB
Views
708 views
File license
Fair use/fair dealing exception

...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

Reply 10 of 27, by alvaro84

User metadata
Rank Member
Rank
Member

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

HGFpIJx.jpg

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

Shame on us, doomed from the start
May God have mercy on our dirty little hearts

Reply 11 of 27, by matze79

User metadata
Rank l33t
Rank
l33t

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..

https://dosreloaded.de - The German Retro DOS PC Community
https://www.retroianer.de - under constructing since ever

Co2 - for a endless Summer

Reply 12 of 27, by Jo22

User metadata
Rank l33t++
Rank
l33t++
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.

Attachments

  • cga_os2_738k.png
    Filename
    cga_os2_738k.png
    File size
    34.51 KiB
    Views
    572 views
    File license
    Fair use/fair dealing exception
Last edited by Jo22 on 2019-04-13, 18:43. Edited 1 time in total.

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 13 of 27, by Kubik

User metadata
Rank Member
Rank
Member
ipx.jpg
Filename
ipx.jpg
File size
249.67 KiB
Views
577 views
File license
Fair use/fair dealing exception

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

Reply 14 of 27, by root42

User metadata
Rank Oldbie
Rank
Oldbie
alvaro84 wrote:
...but I have a tiny late XT clone too: […]
Show full quote

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

HGFpIJx.jpg

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!

YouTube and Bonus
80486DX@33 MHz, 16 MiB RAM, Tseng ET4000 1 MiB, SnarkBarker & GUSar Lite, PC MIDI Card+X2+SC55+MT32, OSSC

Reply 15 of 27, by Error 0x7CF

User metadata
Rank Newbie
Rank
Newbie
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.

Old precedes antique.

Reply 16 of 27, by Jo22

User metadata
Rank l33t++
Rank
l33t++
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!). 😢

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 17 of 27, by alvaro84

User metadata
Rank Member
Rank
Member

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...?)

Shame on us, doomed from the start
May God have mercy on our dirty little hearts

Reply 18 of 27, by Jo22

User metadata
Rank l33t++
Rank
l33t++

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.

Attachments

  • Filename
    megabyte.zip
    File size
    19.51 KiB
    Downloads
    15 downloads
    File comment
    Several public domain memory utilities, includes 704K.
    File license
    Fair use/fair dealing exception

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 19 of 27, by mdog69

User metadata
Rank Newbie
Rank
Newbie
alvaro84 wrote:
Mut wrote:

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.