Centronics Printer Interface
Interrupt Capability
Set IRQ ENB to logical 1 to enable the interrupt from the printer port.
Set IRQ ENB to 0 to disable the interrupt from the printer port. The
interrupt is generated when the ACK* signal goes inactive (high) and
is a result of the rising edge of ACK*. Therefore, if ACK* remains
high, no further interrupts are generated. For STD DOS use, the IRQ
ENB bit is set to 0, since STD DOS does not use the printer port
interrupt. If using the printer port for general purpose I/O, keep IRQ
ENB disabled unless the ACK* signal is to be used as an interrupt
request input. Be sure also to disable the interrupt request (IR7) at the
8259A Interrupt Controller if jumper W11A is installed so that the
interrupt will not be seen. This should be done even if IRQ ENB is
disabled. STD DOS takes care of disabling the interrupt IR7 in
ZT 8809A DOS systems.
9-9
Содержание ZT 8809A
Страница 15: ...Tables Table B 9 J5 Pin Assignments B 17 Table B 10 J6 Pin Assignments B 18 Table B 11 J7 Pin Assignments B 19...
Страница 334: ...Jumper Configurations W49 W48 A W47 B A B W37 W66 A W50 B C J7 W67 Figure A 11 W37 W47 50 W66 W67 Jumper Blocks A 34...
Страница 346: ...Jumper Configurations W61 W60 W62 W63 W64 A B A B W65 Figure A 13 W60 W65 Jumper Block A 46...