5t4nd1ng @ th3 3dg3 0f 5p3ct4t10n!

Welcome to Walt Perko's Brainless.org-anizm


My Vintage Altair 8800 Computer SN:222820K
First, you can learn more about MITS and the Altair 8800 with simple searches online.


After exploring inside of my new computer and imaging the S-100 circuit boards and other guts, I found this computer once belonged to Fremont School. Now I'm working on tracking it's original provenance.

I found the computer on CraigsList.org and bought the computer from a guy in Mill Valley, CA. that got the computer from a neighbor that died.


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Front Panel is well worn!

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Looking inside


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Not an original MITS Power Supply

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Maybe in the future I'll pull this power supply and reaplce it with Mean-Wells

In the meantime, after testing the power supply to be usable, I was able to add a longer bolt to allow DB25 connectors in the back panel.

It's nice to have the slots further apart so one board doesn't heat the next board.
One more 88-2SIOJP behind the current board and maybe the last light green slot can be a parallel board.
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A closer look at the boards
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Nice Looking MITS 8080 CPU Board


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The Console 88-2SIO board addresses 10h/11h and 12h/13h and setup for TTY rather than RS-232

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The 2nd 88-2SIO board addresses 00h/01h and 02h/03h and setup for TTY rather than RS-232


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Came with the Solid State Music 4K Static RAM board

This board is For Sale or Trade

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Also came with a Tarbell Cassette I/O board


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My Vintage Altair 8800 Computer SN:222820K Back to Life with a Basic Restore
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Original MITS 8080 CPU board,
CompuPro RAM17 w/Monitor EPROM at F800
Processor Technology 3P+S Setup as Console 10h/11h

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The Mean-Well Power Supplies

Digikey.com or Mouser.com or JameCo.com
"RT-65C" for +15V and -15V
and
"HRP-75-7.5" for +8V

Mean-Well-DXF-DrillGuides.zip

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I still need to Laser Engrave a new Front!

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Original MITS 8080 CPU board Rev.0


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Original CompuPro RAM17 w/added 2517 EPROM Containing GWMON-80 1.1 Set to BOOT at Address F800h

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Original Processor Technology 3P+S Addressed 0000h/0001h


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BOOTing to the GWMON-80 Prompt

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Replacing & Improving After the Basic Restoring/Refurbishing
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Keeping the same Original MITS 8080 CPU board

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Replacing the CompuPro RAMN17 with a FDC+ board from FarmTek

deramp FDC+

Allows for 64K RAM and BOOTing to the PC Serial Drive Server serving four Floppy Drives to the computer!

S3 = 00000111 ... S1 = 00000000 ... S2 = 01110000 ... S4 = 00000000

J2 Serial Port DCE via Ribbon Cable to an ESP32 FDC+ WiFi Module which has the four floppy drives (two 8MB and two 370KB)
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Replacing the Processor Technology 3P+S board with a Martin Eberhard 88-2SIOJP board

Address 10h/11h and 12h/13h = 16d/17d and 18d/19d

Console Port 0 and Port 1 are both set to 9600 BAUD

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Adding the PAiA SS100 Versa-Talker

One of the Rarest S-100 boards in the world, the PAIA SS100 Speech Board

Addressing:
Standard Configuration (Ports 30H & 31H)

Standard default Base Address:
(S4) A4 OPEN (1) — Adds 10H
(S3) A5 OPEN (1) — Adds 20H
(S2) A6 CLOSED (0)
(S1) A7 CLOSED (0)
(Total decoded base = 20H + 10H = 30H)
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Installed the Mike Douglas ACR board

I had to drill a hole in the old power supply plate and add a 3mm bolt with three nuts to position the board in place and level so it cannot touch the power supply plate and short anything.

Then lossen the top and bottom bolts holding the back dress panel on so I could slip the ACR board into position with the M3x20mm stand-off bolt into the power supply plate hole.

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To get the two Audio Jacks to fit I needed to drill out the holes to 6.75mm (17/14inch)


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A future addition when I get one is the DeltecEnt 88-2SIOR1 board

Address will probably be 14h/15h and 20h/21h = 16d/17d and 22d/23d

Both Port 0 and Port 1 will be set to 9600 BAUD
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FDC+ Dip Switches


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My First Program for this and other Altair 8800 Computers ... KILLSBIT.COM
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Little Programs for Testing 8080 CPU Computers
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This program sends "A" to "Z" to the serial port

; TEST PROGRAM TO CONTINUALLY SEND A TO Z CHARACTERS TO THE SERIAL PORT AT 10H,11H
; THIS PROGRAM ASSUMES THAT THE SERIAL PORT IS CONFIGURED AND THE BAUDRATE IS SET
; BY HARDWARE JUMPERS ON THE SERIAL CARD.
; BUILD USING ASM.COM WITH CPM COMMAND: ASM SERTST

; DEFINE PORT CONFIGURATION FOR SERIAL PORT 0011 = CONOUT EQU 11H ; SERIAL PORT DATA OUTPUT PORT
0010 = CONSTAT EQU 10H ; SERIAL PORT STATUS INPUT PORT
0002 = CONTBR EQU 2H ; SERIAL PORT TRANSMIT BUFFER READY STATUS BIT
. . . . . . . . . . . . . . . . . . . . . . ; ASSUMES BIT IS HIGH WHEN THE UART IS READY TO SEND A CHAR

0000 ORG 0

START:
0000 0E41 MVI C,'A' ; LOAD REG C WITH ASCII A ( 016 101 )
LOOP:
0002 DB10 IN CONSTAT ; READ CONSOLE STATUS PORT ( 333 020 )
0004 E602 ANI CONTBR ; CHECK TO SEE IF UART IS READY TO SEND A CHARACTER ( 346 002 )
0006 CA0200 JZ LOOP ; LOOP UNTIL UART IS READY TO SEND NEXT CHAR ( 312 002 000 )
. . . . . . . . . . . . . . . . . . . . . . ; ASSUMES BIT IS HIGH WHEN THE UART IS READY TO SEND A CHAR

0009 79 MOV A,C ; ACC = TEST CHARACTER ( 171 )
000A D311 OUT CONOUT ; OUTPUT CHARACTER IN ACC TO CONSOLE ( 323 021 )
000C FE5A CPI 'Z' ; IS LAST CHARACTER A Z ( 376 132 )
000E CA0000 JZ START ; YES, RESTART SEQUENCE AT A ( 312 000 000 )
0011 0C INR C ; NO, NEXT TEST CHARACTER ( 014 )
0012 C30200 JMP LOOP ; REPEAT WITH NEW CHARACTER ( 303 002 000 )



; OCTAL CONVERSION SUMMARY AS SHOWN ABOVE IN COMMENTS
; THERE DOESNT APPEAR TO BE A WAY TO GET ASM TO OUTPUT OCTAL LISTINGS
; SO THE CONVERSION WAS DONE A BYTE AT A TIME FROM THE HEX IN THE LISTING FILE.
; LOAD THE FOLLOWING BYTES STARTING AT ADDRESS 0, THEN START EXECUTION AT 0
; OR BUY AN IMSAI SO YOU CAN USE HEX DIRECTLY FROM THE LISTINGS!
;( 016 101 )
;( 333 020 )
;( 346 002 )
;( 312 002 000 )
;( 171 )
;( 323 021 )

;( 376 132 )
;( 312 000 000 )
;( 014 )
;( 303 002 000 )

0015 END START ; INCLUDE START ADDRESS IN HEX FILE

..........OCT .......... ..........HEX
...........016 .......... ........... 0E
...........101 .......... ........... 41
...........333 .......... ........... DB
...........020 .......... ........... 10
...........346 .......... ........... E6
...........002 .......... ........... 02
...........312 .......... ........... CA
...........000 .......... ........... 00
...........171 .......... ........... 79
...........323 .......... ........... D3
...........021 .......... ........... 11
...........376 .......... ........... FE
...........132 .......... ........... 5A
...........312 .......... ........... CA
...........000 .......... ........... 00
...........000 .......... ........... 00
...........014 .......... ........... 0C
...........303 .......... ........... C3
...........002 .......... ........... 02
...........000 .......... ........... 00

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Hand Coded Page by Walt Perko