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.
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?
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.
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
00002
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
00007
0008 47 [5] 00008 mov B,A ; Save the character
00009
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
00014
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
00019
0017 00020 Done
0017 76 [7] 00021 hlt ; Stop
00022
0018 48656C6C6F20776F 00023 Hello db 'Hello world.'
0020 726C642E
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…
