I recently built an Apple I clone.
I went through all the key milestones successfully.
1) Video circuit outputting an all "@" screen
2) Processor circuit reset and giving the'/' prompt
3) For the last milestone (running the test program to print all ASCII characters),
I bought an Apple II SMC KR3600 keyboard encoder from eBay and used an old 1984 Macintosh keyboard as my donor keyboard.
I removed the chips and proceed to cut and rewire all the traces as per an Apple II keyboard matrix.
Surprisingly, this worked out very well. All the alphabetic, numeric and special characters work as well as the shift and control keys.
I was able to enter the ASCII test program and run it on my Apple I clone.
I have not been able to get the rubout (<-) key to work.
It is wired as per the Apple II keyboard matrix (two piece keyboard).
Has anyone got their rubout key to work in a similar setup.
I have seen posts with it working for MM57040 based keyboards.