Altair 8800 mini-clone up for grabs


Hey guys, I have an Altair 8800 clone that I put together a number of years ago. It boots and runs a BASIC image from an SD card. I was not able to get CP/M running on it for Zork, and I moved on to other projects.

Original info here:

Comes with a PS/2 Keyboard for control and power supply, has a TV and VGA output. Hardware is emulated on a Parallax Propeller, but front panel is fully functional.

It would be nice to recover a few bucks for this, maybe $40 or so?

[Project Log] Python on the 6502/C64, 8080, 6800, 6809 and AVR

I would like that please. I’ll bet I can get CP/M to run.

I’ll probably be at The Space next on Friday for the Member Meeting/Potluck.


Tisk tisk. Misleading title … clone implies hardware was duplicated. This is an emulator.


It was cloned: the front panel in hardware, the architecture in software. It even has an S100 (ish?) expansion bus inside.


Meh. Not in my book. Emulator.


This is what I get for being out of town.

I’m building an S-100 system and went on a road trip to pick up 4 8" floppy drives… just got home.


You got a link or is this a homebrew?



I have an N8VEM backplane, a Wameco 8080 CPU board, and a couple of California Computer Systems cards - memory and serial/parallel interfaces.

I have to figure out a front panel and a monitor ROM.


Now that is a worthy Altair 8800!

Have a source for the front-panel switches?

(edit: I want Lightman’s IMSAI 8080…)


Pulled the trigger on this one since the backplane has a slot specifically for this card.

I have to still find switches worth of it… and +8v, +16v, and -16v power supplies.

Once I put the backplane together and find power supplies I need to build a case for it.

Edit: Here’s more info on the front panel card:


I have the backplane built as far as I could get it with the parts I had here in the shop and that Jim Tanner has at his place. I have to order a few things to finish it out and hope to do that today or tomorrow.

I did at least hook it up to my Tektronix power supply and fed it +8, +16, and -16v to verify the LEDs were installed correctly and that the voltage regulator was working. I had to adjust one of the 20k resistors down to 1k to fix the brightness on the -16v power indicator LED. Not sure why they went with such a high resistance.


If you need help bringing CP/M up on it, I have done CBIOS work in the past.


Thank you again, Daniel.

The good news:

  • It is a really nice little box.
  • I have never used an Altair, being an IMSAI guy, but they are similar enough that the front panel makes sense.
  • The video VGA port and PS/2 keyboard port emulate a terminal connected to an ACIA at I/O addresses 10H and 11H.
  • It appears the binary files on the SD card are just raw memory dumps. I will try to load my own assembly language programs that way.

The bad news:

  • An add-on memory and disk emulator card is needed to run CP/M so I will have to find one somewhere. The Briel web site seems to indicate they do not have any more.

For grins, I tried this program:

 0000 21 0018	     [10] 00001		lxi	H,Hello	; Point to message
 0003			  00003	Loop
 0003 7E	      [7] 00004		mov	A,M	; Get a character
 0004 B7	      [4] 00005		ora	A	; Is it the end?
 0005 CA 0017	     [10] 00006		jz	Done	; Yes
 0008 47	      [5] 00008		mov	B,A	; Save the character
 0009			  00010	Wait
 0009 DB 10	     [10] 00011		in	10h	; Get port status
 000B E6 02	      [7] 00012		ani	2	; Transmitter ready?
 000D CA 0009	     [10] 00013		jz	Wait
 0010 78	      [5] 00015		mov	A,B	; Recover the character
 0011 D3 11	     [10] 00016		out	11h	; Write the character
 0013 23	      [5] 00017		inx	H	; Point to next character
 0014 C3 0003	     [10] 00018		jmp	Loop	; Repeat
 0017			  00020	Done
 0017 76	      [7] 00021		hlt		; Stop
 0018 48656C6C6F20776F	  00023	Hello	db	'Hello world.'
 0020 726C642E

with this result:

If I flip the AUX switch on the front panel and step through machine code, the monitor displays detailed information!!! If only it was this good with the original…


So glad you have the time and motivation to get this gear to do something!

Yeah, it’s a shame about the disk, although it might be possible to make your own (with some trouble) if you’re so inclined: