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3-4-2. Wait control
0 Function
Wait is a function applied
in
acc
es
si
ng
a slow action memory.
It
mak
es
the CPU
operation temporarily ha
lt
ed
until a complete access is done to the slow action
memory.
When the CPU makes access to the address
whe
re slow action memory is
assigned. the condition
"I~
is
en
tered to the
wa
it
co
ndition inputs
WO
and W
I.
WO
is
the wait
co
ndition input
wh
ich is applied to
pl
ace
wai
t to the memory
ar
ea controlled
by
ME
O.
wh
ile WI is the
wa
it condition for the memory area contro
lled
by ME
I.
W
he
n t
he
wai
t condit
io
n is estab
li
she
d.
that is. when
"WO·
M
E(}l-W
I· ME 1= 1"
is
met,
the
WAI
T signal is
iss
ued to t
he
CPU.
As
the
wa
it
co
ntrol counter is provid
ed
internally. it relea
ses
WAIT to the CPU
wh
en it
is
counted to the value set by the
program. then
th
e CPU proceeds to execute a ne
xt
machine cycle.
AD
MEO
WO
\_
WA
IT
"---
rn
cremenlS couotcr
---'
=>
WA
IT
re
l
e~sed
DM
EO
~-
(
P
-;.----
tA
---
_,,
Si
nce
a slow access memory usua
ll
y consists
of
dyna
mic
logic.
it
needs a
pr
echar
ge
t
im
e
(
tr
).
Thus. the 1/ 0
port
controller issues the memory e
nal:>
lc signa
ls
DM
EO
and
DMEI
to the dynamic memor
y.
including the precharge time. DM
EO
is for MEO
and
DME
I is for ME
I.
When the CPU accesses the 1/ 0
port
controll
er
, the signal
WAIT
is
iss
ued
wi
thout
the
wa
it
co
nd
iti
on
in·
WO
and
WI.
® Wait time
Wai
t time can
l:>e
programm
ed
by means
of
b
it
positions of G5. 6 and 7
of
the G
registe
r.
Re
la
tion
of
GS.
6.7 with tA and
tr
refer to page
70
.
75
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not
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