The Lisa I/O Board uses a custom mask programmed COP421 to interface with the mouse and keyboard and provide a real time clock with alarm/wake-up.
The Lisa I/O programmed parts are typically labelled either COP421-HZT/N or with the Apple part number 341-0064.
COP421 ROM code: https://bitsavers.org/pdf/apple/lisa/hardware/COP421/ (https://bitsavers.org/pdf/apple/lisa/hardware/COP421/)
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custom mask programmed COP421
As these are custom made parts with Apple's programming, they are not easily replaced if damaged or missing. A randomly selected (eg. from eBay) COP421 is likely to have different programming in it.
If you need to replace one, you can:
- DIY using Patrick's COP emulator design (http://john.ccac.rwth-aachen.de:8000/patrick/COPSreader.htm)
- Purchase assembled and tested from VintageMicros (http://vintagemicros.com/catalog/xcops-replacement-device-original-lisa-cops-chip-p-306.html)
There is a three-letter code printed on the chip that indicates the ROM mask. For our Lisa we have HZT for the I/O and KPK for the Widget motor. Somewhere I have a third ROM dump from an automotive control unit.