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caius

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Recently I have been working on reproducing the custom chips found on Irem M72/M82/M84 hardware.

Often these chips have scratched-off part number (especially in later hardware like M82/84) but on my R-Type PCB (M72) they were visible so I started my work with the 'KNA70H015(11)' (SDIP64) and 'KNA70H016(12)' ( DIP48 )

Irem%2B%2527KNA70H015%252811%2529%2527%2Boriginal.jpg



Irem%2B%2527KNA70H016%252812%2529%2527%2Boriginal.jpg

Functions of these chips are not really clear due to scarce info available, we have only the pinout from schematics so I studied them at 'low level" looking at previous hardware and trying to guess their functions.TTL thru-hole prototypes were done after some time :

70H015%252811%2529%2527%2Breproduction%2B-%2BCopia.jpg



70H016%252812%2529%2527%2Breproduction%2B-%2BCopia.jpg

Testing of both prototypes was successful on different boards :

View: https://youtu.be/zvSD9p8amAY


View: https://youtu.be/3PeQZNuUZiE


This achievement opens obviously the way to implement the equivalent circuit on complex programmable logics for proper replacement of the original chip as well as making possible a multi board or a FPGA emulation.Stay tuned for further updates about reverse engineering of the other Irem custom chips.
 
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