Sharp MZ-5500 Tehnical Manual

3-3. System interrupt (lR-25) specification
The MZ-5500/5600 expansion slots have several interrupt request input lines,
and the 1R-25 is used for system expansion. As it supports multiple
interrupts of eight levels, attention must be paid to the following points
when designing the interrupt cireuit.
i) Hardware
Sinc e the 8259A lnterrurt Controller issues the interrupt to the CPU with a
high state of an interrupt request input (low on the 1/0 slot), the interrupt
r equ e st signal has to be r e tained until the CPU reeognizes the interrupt.
Th e re for e , there i s a ne ed of using the deviee that ean elear the interrupt
r eque st by th e s o ftwa re or the software that elears it on the 1 /0 port. As
As
tlle IR-25 int e rr oga t e s multiple interrupt by a software polling, it i s so
d cs i gned as to de t cc t t~ e device with the interrupt request on the r/o port.
a) ~~en the interrupt elear and port output functions are hardware comprised.
tsv
IR-2S"
D
(.
'J1: 0,,-/)
~-~
J...-------t ; NT
f)11
,0 Re.
1/0 deLc ·
(e>. : fCDH )
AiDW(
b) When using the deviee that has the interrupt clear funetion.
o~ U: ' I\:dbr-
~~-------------;;~
D1t
1J 1 0,,15
;oRc
J!a d~~c\~
(e;t0 1(0\4)
c) \.Jhen using the device that has the interrupt clear funetion and the
internal register interrupt request flag sensing funetion.

Sharp MZ-5500 Specifications

General

Brand	Sharp
Model	MZ-5500
Category	Desktop
Language	English