Patch into the INT 1Ch interrupt vector. Okay, ints back on. DOS TSR command. The keyboard microcontroller also sends data to the on-board microcontroller for processing and release to the system through port 60h. Any particular, any program that sends commands to the keyboard needs to be able to handle the resend and acknowledge commands that the keyboard microcontroller returns in port 60h.
System sends a zero byte as the last value when the keyboard controller's internal buffer overflows.
AA Returned during basic assurance test after reset. Also the up code for the left shift key. EE Returned by the ECHO command. Keyboard requests the system to resend the last command. Therefore, the keyboard interrupt service routine normally handles all the above codes.