
PC-Retro Motherboard Kit: Build a faithful reproduction of the 1982 IBM PC 5150 - peter_d_sherman
http://www.mtmscientific.com/pc-retro.html
======
acd
Related to IBM PC keyboards

Unicomp modern versions of the IBM Model M keyboard built iwth the same
tooling that made the originals. When living in a flat share I had access to a
IBM Model M keyboard the one made for the PS/2 computer. This is one of the
best keyboards I have ever used they are built like tanks.

Unicomp keyboards [https://www.pckeyboard.com/](https://www.pckeyboard.com/)

~~~
perl4ever
I tried a "buckling spring" keyboard (I think from Unicomp) that was supposed
to be the equivalent of one of those IBMs and I was severely disappointed in
the electronics. It could not handle multiple keys properly the way a real one
would. Basically they had focused completely on the selling point of the
springs and neglected to make a usable product.

(I did have a real PS/2 Model M previously, so all I really wanted was a USB
equivalent)

~~~
throwaway2048
The USB HID standard has a limit of 4 keys pressed at once, unless you do
fuckery like virtual USB hubs with additional virtual keyboards (which will
cause some things to misbehave) there is no way around this restriction
without custom drivers (which are also a nightmare).

~~~
ddingus
TIL

By chance, do you know the limits on real PS/2?

~~~
userbinator
Effectively none --- the keyboard only sends "key X is pressed" and "key X is
released" messages.

On the other hand, the key matrix design can impose its own limits.

~~~
deaddodo
To expound on that: The matrix in most PS/2 keyboards only supports two-key
rollover (reliable detection of two keys pressed at once). In the case of
three+ keys there is a chance for missed presses and other artifacts.

~~~
ddingus
Thanks as well.

------
magoon
I remember upgrading the RAM from a paltry 128KB (i think). See all of those
empty sockets?

Notably missing, and fair warning:

\- Floppy controller

\- Floppy drive! 5 1/4”

\- Hard drive controller (RLL)

\- CGA or Monochrome Display Adapter

\- Serial port adapter if you want to modem (25-pin 16450 UART)

\- PC-DOS

Good luck. These are harder than you think, have no sound but a “beep”, and
can’t even keep the time between reboots.

~~~
dsr_
Even if you can find a CGA or MDA, good luck finding a surviving monitor to
display it.

Honestly, you're probably better off finding an intact PC on ebay or
Craigslist or such.

And for doing anything practical, much better off with a Raspberry Pi variant.

~~~
kw71
with regard to displays, gbs-8200 will help here.

~~~
eltoozero
Gonbes GBS-8200/8220 CGA/EGA/YUV to VGA Arcade HD-Converter PCB allows all
types of RGB, EGA, VGA or YUV component signals to be up-converter and display
on a 31KHz PC VGA monitor, TFT monitor, LCD display, or HD-TV with VGA
connection. No need to set dip switches in order to figure out the specific
input frequency as all inputs are detected automatically! A great alternative
to purchasing a expensive, heavy CGA monitor.

[0]: [https://www.mikesarcade.com/cgi-
bin/store.pl?sku=GBS-8200](https://www.mikesarcade.com/cgi-
bin/store.pl?sku=GBS-8200)

------
userbinator
The "anonymous BIOS" is just begging to be replaced with a copy of the actual
IBM BIOS (whose source code is also available), but I guess they decided not
to supply it for copyright reasons; on the other hand, they did clone the
hardware... I bet it raises all sorts of difficult questions for the IP
lawyers.

~~~
deaddodo
IBM themselves released the board schematics for the 5150.

~~~
peter_d_sherman
You wouldn't have a link, would you? I'd be interested in this...

~~~
b11484
[http://www.minuszerodegrees.net/manuals/IBM_5150_Technical_R...](http://www.minuszerodegrees.net/manuals/IBM_5150_Technical_Reference_6322507_APR84.pdf)

This is the technical manual for it

~~~
peter_d_sherman
Thank you very much! Much obliged!

------
jchw
This is so very tempting, yet I know well I don't have the time or patience to
set one of these up. I hope we'll at least see some of these pop up on
YouTube, I'd love to watch someone assemble and use one of these.

------
raverbashing
And after you put it together, remember you need a power supply, a CGA? card
and a keyboard to use it (and a DD or HD if you want to do anything besides
looking at a screen)

~~~
Narishma
I believe it was possible to use the original PC with cassette tapes instead
of floppies, though you'd be limited to ROM BASIC in that case, and not PC-
DOS.

~~~
LeoPanthera
There's a reason why DOS stands for Disk Operating System. :)

~~~
wolfgke
> There's a reason why DOS stands for Disk Operating System. :)

This is a retronym. Before purchased by Microsoft, DOS was developed by
Seattle Computer Products under the name QDOS (Quick and Dirty Operating
System). This was changed by Microsoft to MS-DOS with a changed meaning of
"DOS".

~~~
LeoPanthera
Sure, that's correct. But the new name of "Disk OS" was completely relevant to
this specific PC.

------
jacquesm
That's a pretty kit and that was a very large amount of work, congratulations
on seeing it through. I suspect there is a larger market for a more complete
offering, so maybe tackle a graphics board next?

I believe this video is about this project:

[https://www.youtube.com/watch?v=fCe0I3RJajY](https://www.youtube.com/watch?v=fCe0I3RJajY)

If you want to go the 'soft' route of emulation then there is this:

[http://www.hampa.ch/pce/download.html](http://www.hampa.ch/pce/download.html)

~~~
Narishma
PCem is more accurate, supports more hardware and is easier to use.

[http://pcem-emulator.co.uk/](http://pcem-emulator.co.uk/)

~~~
Zardoz84
Is this emulator ?
[https://youtu.be/Vg2n8Fp7F2g](https://youtu.be/Vg2n8Fp7F2g)

~~~
Narishma
Yes, though that seems to be a fork and not the official version.

------
DoofusOfDeath
I'm amused by the timing of this article. I just watched the anime series
"Steins;Gate", and a major plot element revolves around getting a working
5150.

~~~
ashleyn
Steins;Gate undoubtedly got it from the John Titor urban legend.

------
corerius
I'm waiting for the full 3270 PC or the XT/370 kit.

------
Animats
Why don't they stuff the board? It would probably cost less than packaging the
parts and dealing with customer service issues.

~~~
auvrw
perhaps the

> Obviously, this is a project for an advanced electronic hobbyist and
> computer enthusiast.

is somewhat tongue-in-cheek: this could be the thing to get a kid who's
already soldered together a bunch of (less expensive) analog hobby kits .. or
the adult who's into that sort of thing.

it's pretty much the same thing as building model cars, airplanes, etc.
although it doesn't teach you exactly how the thing works, the perceptual task
of doing the soldering and checking out the traces gives some idea of how
things piece together.

as far as vintage electronics go, IBM PCs (probably?) aren't that difficult to
find for those who're essentially interested in abstracting away from the
hardware.

------
yjftsjthsd-h
DIY and hacked together out of third-party pieces? Yep, that's an authentic PC
_clone_ alright:)

~~~
peter_d_sherman
I use the word "reproduction" because "clone" in the context of the Original
IBM PC is/was an ill-defined word which means different things to different
people:

[https://en.wikipedia.org/wiki/IBM_PC_compatible](https://en.wikipedia.org/wiki/IBM_PC_compatible)

When some people think "clone", they think "compatibility" which leads to the
following differences:

Excerpt:

"In May 1983, Future Computing defined four levels of compatibility:[11]

Operationally Compatible. Can run "the top selling" IBM PC software, use PC
expansion boards, and read and write PC disks. Has "complementary features"
like portability or lower price that distinguish computer from the PC, which
is sold in the same store. Examples: (Best) Columbia Data Products, Compaq;
(Better) Corona; (Good) Eagle.

Functionally Compatible. Runs own version of popular PC software. Cannot use
PC expansion boards but can read and write PC disks. Cannot become
Operationally Compatible. Example: TI Professional.

Data Compatible. May not run top PC software. Can read and/or write PC disks.
Can become Functionally Compatible. Examples: NCR Decision Mate, Olivetti M20,
Wang PC, Zenith Z-100.

Incompatible. Cannot read PC disks. Can become Data Compatible. Examples:
Altos 586, DEC Rainbow 100, Grid Compass, Victor 9000."

So what type of a "clone" are we talking about?

I don't work for the company that makes the kit, and as far as I can tell
prima facie, their kit is a faithful reproduction of the reference IBM PC
hardware design.

I may be wrong, however.

~~~
ido
Very shortly after this article was published nobody was using the term in any
way but the top one (nor were less than 100% compatible PCs even sold for much
longer).

My parents bought our first “ibm compatible” in 1987 and even back then the
degree of compatibility was already a complete non-issue.

