Quote:
Originally Posted by ortek_service
I presume the scanning is all done via regular interrupt timing, otherwise it would slow programs down a lot if it sat constantly reading the other (column) side of keyboard matrix, for the whole complete keyboard scan time..
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Yes, one of the interrupt pins on one of the IO chips is connected to the vertical retrace signal, and the keyboard is scanned in the interrupt service routine which also adjust the real time clock, flashing cursor etc.