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)
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 :
Testing of both prototypes was successful on different boards :
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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