![]() ![]() I have added an additional 8KB of NV SRAM wired up in the breadboard area. Amazingly my local electronics store ( ) had the 74LS126 in stock as an NTE part and that NTE chip was NOS also dated 1978! Replacing that chip and repairing a few solder joints brought it back to life. I started investigating the circuit and discovered someone had put a wrong logic chip in one of the sockets (it had a 7400 installed, needed a 74126 actually). I bought this device from a Craigslist posting a few months ago and it would power up but was not working. I lusted after this device when I was a young teenager in the late 1970s, but could not afford it then. All interaction is done with the keypad and the 6 digit LED display. It was typically sold in kit form, and assembled by the end user and included sample programs and lessons for learning about low level microprocessor programming in assembly language and basic digital interfacing. It has a Motorola 6800 CPU running at about 500 kHz, 512 bytes of RAM, and 1 KB of ROM. ![]() This is a Heathkit ET-3400 microprocessor trainer from 1978. The seller has not uploaded any pictures. ![]()
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January 2023
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