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Old 15th Nov 2019, 7:48 pm   #16
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 3,156
Default Re: A Simple Programmer for TESLA "MH74S-" bipolar PROMs

Over on the Vintage computer forums there's someone who has managed to acquire himself a National Introkit, generally acknowledged to be the immediate ancestor of the MK14 on which Circuitryboy's Tesla programmer here is based.

The Introkit doesn't seem to be working and one possibility is that the SCMPKB PROM is corrupt, so I'm busy putting together an Arduino sketch specifically to read the 512 bytes of code from the PROM because I know that the owner of the Introkit has a few Arduinos lying around. While in the initial stages of doing this, I have found, to my surprise, that the SCMPKB code which I have and the code for the old / original MK14 OS do not match (The sketch checksums the code as it reads it from the PROM) - I was always convinced that they were identical.

The SCMPKB code I have was created by Youtube user 'CuriousMarc' as part of the process of repairing his own Introkit in his video here:-

https://www.youtube.com/watch?v=fK-IZuIonnY

...so I don't know if it is a verbatim image of the original SCMPKB code. It would be surprising if it was not.

The Old / original MK14 OS code I have came from a quiet corner on Martin Lukasec's website, and again I don't know if that was entered afresh by someone working from the listing or whether it was read directly from original 'Old OS' PROMs.

Should they be identical? I've always thought the SCMPKB OS code and the early MK14 OS were one and the same.

I've been testing this using a 'modern' eprom programmed with various OS images - one additional obstacle when reading a real MM5214 PROM is the need for a -12V supply in addition to +5V.
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