I have been working on one of the original ][e computers (white keys).
There are several keys that just will not register no matter what I have done.
Here is a list of what I have done.
I have replaced all the ][e enhancment chips - which someone else put in, with the original chips.
Replaced keyboard rom
Replaced memory with new
Replaced keyboard with known good keyboard
Re-flowed solder on the back of keyboard connector and checked for cold solder and traces
Cleaned keyboard connector pins
Still have the same characters not responding.
Is there something I am missing?
Which keys don't register?
Did you check the socket of the keyboard encoder chip?
The keys that do not respond on either keyboard are the same:
5 6 DEL T V \ G J R E T N M UPARROW ~
The socket for the keyboard rom has been cleaned and looks good
I tried another keyboard rom and it did not solve the issue either.
Thanks for any assistance in this issue.
I see a 8 byte pattern where bits 0 and 1 are missing that are needed for many, but not all, of those characters.
There must be some chip or component causing the issue. Something the kernal does not pickup.
All of the bad keys connect to the Y5 and Y6 inputs of the Keyboard Encoder. When you said that you tried a different keyboard, did you mean that you plugged in another keyboard to the motherboard socket?
Here is a keyboard Yn, Xn matrix for the IIe keyboard and keypad. Y7 & Y6 related keys are indicated 7 times for the keys mentioned that do not respond, Y3 - 3 times, Y4 - 2 times. X1 - 4 times, X3 - 3 times, X2 - 2 times, with other combinations less.
2e_keyboard matrix.jpg