Hello there,

On a vintage computer the ascii keyboard is connected to a parallel port.
Usually I have a real 6522 via for this port and this works very well.

I try to change the 6522 for a W65C22 and then start to see some strange things.
Some characters (as far I can see "g", "O", "o", "w", "?" and "7") sometime come in twice.
I double check the strobe signal and I am sure that there is only one down pulse per keystroke as expected...
If I read the datasheets (6522 and W65C22) I understand that the data on port is read one time when strobe go down and then is latched until the central processor read it. Only at this moment new data on port can be taken in account.

I must say that I am a little lost and cant understand how this is possible and why only some chars show the problem ???

Any help will be appreciated.
Thanks.
Philippe

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

I have a S version.

Asap I will give a try to a N version.

Regards.
Philippe