Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

HANEL

OTHER MODES OF THE 82558255 in Mode 1:

I/O With Handshaking

Capability

(cont

‰ ’)

The following paragraphs provide the explanation of and reasoning behind handshaking signals only for port A, but in concept they re exactly the same as for port B¾OBFa (output buffer full for port A)

ƒan active-low signal going out of PC7 ƒindicate CPU has written a byte of data in port A ƒOBFa must be connected to STROBE of the receiving equipment (such

as printer) to inform

it that it can now read a byte of data from the Port A latch