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H > HEATHKIT  > H8   


This early computer was to be used with a terminal for better control.

A lots of expansion boards were available for this computer. Memory boards were available in 4K, 8K, and 16K (note: 4k memory board was 8k half populated.)

The H8 was sold with software: Benton Harbor BASIC, the HASL-8 2 pass assembler, TED-8 Line oriented text editor and BUG-8 terminal console debugger.


Further information from John H. Swalby:
Built, used, developed on H8 from 77-84. no longer have any hardware, manuals, etc. just some old photos.
1) the keypad is Octal, as is the display. in fact, the 8080 is basically an octal oriented machine. the instructions are mostly based on 3 bit source and destination fields. Heathkit's early software offerings were all octal. HASL & Bug-8. they used a peculiar bastardized version called "split octal" where each word is represented by 2 octal bytes. so address range looked like 000 000 to 377 377 (0x0000 to 0xFFFF) as opposed to 000000 to 177777.
2) As the product matured, Heath offered a CPU replacement card based on the Z80. This ran CP/M instead of HDOS. Also most of Gates' early stuff, ASM-80, BASIC-80, FORTRAN-80, etc, also UCSD-Pascal p-system was offered.
3) Chassis had large unregulated power supply. Up to 2 regulators were mounted on an aluminium bracket on each card to spread out the heat dissipation. There was no motherboard per se. There was an 88 pin 'backplane' along the right side of the box. The cards were mounted at an angle roughly parallel to the front panel. This was to optimise convection cooling. There were NO FANS. There was a small speaker to beep and add key-clicks for the keypad.
4) Add on cards included: 2-port serial I/O for terminal and casette recorder interface; 4-port serial I/O; H17 floppy disk interface; 2-channel D/A card with 4 part music synthesis software; parallel interface card (possibly for high speed (300baud) papertape reader/punch).
5) The H17 floppy drive was a separate box connected by a ribbon cable. It supported up to 2 - 5.25" full height Wangco drives. Disks were 10 sector - hard sectored floppies. This means there were 11 index holes around the hub. 1 for start of track, and one for each sector! These were VERY expensive. $65.00cdn for a box of 5. Under HDOS they held 104K, under CP/M 80K, formatted. Usually O/S, editor, compilers, utilities were on the first disk; while sources, objects, lists, and user executables were kept on the second.

Jacques Trepanier remembers:
My father bought one in june of 1976 and we were members of the HUG (Heathkit User Group) in Montreal, Canada in 1977.
We ran Benton Harbor basic (from heathkit) and I programmed the 8080 directly using the 16 key keypad. We had an audio tape cassette and a H9 monitor converted to display 24 X 80 caracters (originally it was 12 X 80.
The computer built in language was not hexadecimal, it was split octal.
Also, the computer came with 256 bytes of RAM. You had to buy memory boards, either 4k or 8k. The 4k board was a half populated 8k board. In 76-77 a 8k RAM board was worth $1000 canadian in Montreal.
The H8 had a built-in speaker and it biped when you turned it on. Some people developped music programs in machine language and you had to modify the speager circuitery to play music. It was an RC (Resistor Capacitor) filter if I remember correctly . Our computer play New York new York and The Sting among other popular songs. We copied that music from US magazines.

Please consider donating your old computer / videogame system to or one of our partners from anywhere in the world (Europe, America, Asia, etc.).


I found an h8 and h9 monitor. The h9 works the h8 needs work. I have all manuals and schmatic and documents related to this machine. also correspondence between original owner and heath kit company. email me if interested I can send pictures and more info.

Saturday 24th February 2018
David Hansen (IOWA USA)

The H8 with the H9 monitor was my first computer. I built in in my dad''s basement just before I was transferred to Germany. I was 32 years old and had dabbled in programming for years. (Took BASIC class at BYU in 1964). The H8 was built like a tank! the 32K static RAM ran hotter than the fires of Hades. I think the all steel construction was part of the heat sink design. I loved that computer. I went on to become an IT manager for the federal government and it all started with my beloved H8! I wish I still had it!

Saturday 21st January 2017
Dave Johnson (United States)

The boards I had are now gone. A couple of folks did contact me and bought up what I had. Still have fond memories of the years I had my H8! Good lucking finding parts/boards for those looking.

Saturday 10th December 2005
Paul Domholdt (Los Angleles, CA)


TYPE  Professional Computer
YEAR  September 1977
KEYBOARD  16--key Octal
CPU  Intel 8080 A
SPEED  2.048 MHz
RAM  256 bytes (upgradable with memory boards)
ROM  1 KB in basic version
TEXT MODES  N/A - Small display on the front panel displays the registers content.
SOUND  Built-in speaker
SIZE / WEIGHT  Unknown
I/O PORTS  Serial IO (H8-4) and Cassette Interface (H8-5)
BUILT IN MEDIA  Optional ECP-3801 Cassette Recorder / Player
OS  HDOS, CP/M with extended system
POWER SUPPLY  Built-in power supply unit
PRICE  From $499

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