LisaList2

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/

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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
• Purchase assembled and tested from VintageMicros

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.