Sharp PC-1500 - Page 23

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2-3-2. Interrupts
fh crc arc follo"i ng 1hr ec kind;. of interrupt for th e I 11 5801 CPU.
© N on -m as kable interr upt
W he n NM I is turned fro m low 10 hi gh level. it sc is the nipOop I ROac1i vc. upon which
time
imcrrupt is requc,tcd to th e CPU. so that t he (' PU starts exec ut ing the int cn upt
procc;.;.ing after
com pl etion of curretll in struction execution.
incc the non-maskah
lc inlcrrupt is given with th .: highest priority order. the rntcrrupt
11 ill be ac i..now le dged at on t'C. regardless of its internal ;.late.
I RO wi
ll he rc >et in a course t>f the interrupt pr oc.:s;..
As th e NIM input is sampled by th e clock <J> H. it wi ll b t:co mc 250k H7 when th e 4M H7
Cr)' ta l osci lla tor is connected.
CPU 111lemal
.::"L .. .f---S-j ,... I-"
~ _ _____ __,
NMI
Synchr 0<1 w ng
pulso
IR O- ---- -'
lnstr vc oon ox cc ut o
lnt c: •r lJ PI
ack1 \0 wledP. tt
In t er r up t proce ssr ng
\
,..-" R oso l I RO
When :'llM I is turned high. the Cl' creates synchroni1ing pul se at t he rising edge ol the
clock <J> ll. which se ts IRO :mi1c. If !RO is act ive when the CPU acknc> " lcdged the
int
er ru pt lifter comple tin11 of e xe cut io n. it goes int o t he interrupt rout ine <Jnd I RO i' reset in
a
course of th e interrupt proccs si 11 g.
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