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H > HEATHKIT / ZENITH  > ET-3400   


The Heathkit/Zenith MicroComputer Learning System model ET-3400 was a very popular item designed to teach principles of computers and programming at Universities in the 1970s., and to educate the students of internal computer hardware and software components by self-assembly and programming the machine in pure Hexadecimal language.

It was delivered in assembled or Kit form. It also featured a prototype area and could be used as a design aid for developing special interface circuitry with common 6820 parallel interface or 6850 asynchronous chips.

Several software in ROM were also available. Among them an Assembler and a Tiny BASIC.


Mendel Cooper's memories:
I built one of these from a kit back in about 1984, I guess. Price was approx. $200 in kit form.
Heathkit used to sell three educational courses based on the ET-3400:
1) Microprocessor Course, EE-3401
2) Microprocessor Interfacing Course, EE-3402
3) Microprocessor Applications Course, EE-3405
Using the specs in the manual, it was pretty easy to build homebrew memory expansion. For a couple of dollars worth of parts, I built a 2K module, using a 6116 (2K x 8) static RAM chip.

We need more info about this computer ! If you designed, used, or have more info about this system, please send us pictures or anything you might find useful.
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Just picked up one of these trainers today at the Scottsdale ARC Hamfest$ got the trainer and a few mostly-complete "courses" (the trainer itself had some extra parts and whatnot on the breadboard, with wires running to various sections). I''ve been scouring the web looking for more info and such, and have found quite a lot. I found a PDF copy of EE-3401 - I''m looking for PDF copies of EE-3402 and EE-3405$ does anybody have ''em?

Saturday 9th March 2013
Andrew L Ayers (USA)

I currently have a complete set of the et-3400 manuals with tapes records and schematics on sale on eBay! They are in great condition. I have schematics as well as all Tests!

Sunday 25th September 2011
Michael Wagg  (United states)

Would anyone on this topic know someone who owns the microprocessor continuing education manuals? I just sold the two manual set and the buyer discovered a couple of missing sections which I would rather replace somehow than just refund.

Any help would be greatly apreciated.

Saturday 10th September 2011
Tim Niles (Minnesota)


NAME  ET-3400
MANUFACTURER  Heathkit / Zenith
TYPE  Home Computer
YEAR  1976
KEYBOARD  17 keys Hexadecimal keypad
CPU  Motorola 6800 then 6808 (1981) and 6802 (1987)
RAM  256 bytes expandable to 1 KB
TEXT MODES  6 x 7-segment LEDs
SIZE / WEIGHT  30.5 (W) x 30.5 (D) x 10.15 (H) cm. / 2 Kgs
POWER SUPPLY  External AC adapter
PERIPHERALS  Prototype area
PRICE  $199.95 Kit, $279.00 assembled, $99.95 for the ET-3401 course

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