Sharp MZ-80B - Page 89

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Figures 3.0-SA and 3.0-SB illustrate how a programmable counter can be used to extend interrupt acknowledge
time. (Configured as shown to add one wait state)
LAST T STATE · o~ I
LAST M CYCLE OF
IN STRUCTION
IORQ
74S04
+ 5V
~ IORQ
~Q-~-TE-~-1-P_H_E_R - AL )
B
WAIT
,.-----+--0
7432
Q- ( -T_O_C_P_U_ )_
_ 1.::\
MI--{)L:J
EXTENDING INTERRUPT ACKNOWLEDGE TIME WITH WAIT STATE
FIGURE 3. 0-5A
AUTOMATIC WAIT-\----- ~ \
USER WAIT
Tw *
Tw •
DATA BUS -------------_, _______________ -+-----~-----~~
WAIT
NORMAL ACKNOWLEDGE
TIME
f.---ACKNOWLEDGE TIME WITH ONE
ADDITIONAL WAIT STATE -----+
REQUEST/ACKNOWLEDGE CYCLE WITH ONE ADDITIONAL WAIT STATE
FIGURE 3.0·5B