Sunday, 11 July 2021

Taito 'PC050CM' reproduction

Recently I've been asked to look at the Taito 'PC050CM' in order to study a replacement.It's another custom IC you can find on arcade PCBs from '80 like Rastan, Rainbow Islands, Operation Wolf, Chuka Taisen, Dr. Toppel Tankenkai, Kuri Kinton, Continental Circus and others.The chip has a SIL28 ceramic package coated by epoxy :

Regarding its functionality, the 'PC050CM' handles coin inputs and counters/lockouts as Rastan schematics shows :

If you encounter a bad 'PC050CM' the board won't boot and you will get an error message on screen:

I took on the task to study a replacement for this chip.First of all I tried to "decap" it but it was useless because there are only bare silicon dies under the coating.So, I used a different approach and tried to reproduce the functions building my guess on previous Taito hardware.I made a design based off the 'PC030CM' which is a similar Taito custom IC which I aready reproduced in the past :

Taito 'PC030CM' reproduction

After some time I came up with a prototype on breadboard that worked fine :


The next step was to route a proper board which I did being careful to respect the dimensions of original part  :

Testing was successful on my boards :

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