A SERVICE OF

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8259A
ocw,
~
07
~ ~
~
~ ~
0,
~
I 0
R I SEor I
EOI
I
o i 0 1 c, 1
c,
1 c, I
I
BCD
LEVel
TO
BE
RESET
OR
PUT
INTO
LOWEST
PRIORITV
0
,
2
,
.
6
7
0
,
0
,
0
,
0
,
0 0
,
,
0
0
, ,
0
0
0
0
, ,
, ,
1 r
J-
r+
NON-$I'ECIFrCEO.
~-'i-r+
SPECIFIC
eol.
lO-L2 CODE
OF
IS
Ff
TO
BE
RESET
r,-o~
ROTATE AT Eor AUTOMATICALLY (MODE A)
I-i-r,-r-;-
ROTATE
AT
EOIIMOOE
BI,
(LG-U
OEFINES
NEW
LOWESTPRIORITV)
I-i-Io'o
SET ROTATE A FF
r,-r,-r,-
CLEAR ROTATE A
fF
f7r-;-~
AOTATE PRIORITY (MODE
B)
INDEPENDENTLY
OF
EOI
(LO-U CODE
OF
LINE)
tttttt
NOOPERATLON
ocw,
I 0 1 -
I"M"I
SMM
1 0 1 ' 1 p 1 ERIS 1
R'S
I
OJN'T
l_
READ IN SERVICE REGISTER
CAR~
0
I
,
0
,
0
I
0
, ,
READ REAO
NO
ACTION
IR
REG ISREG
ON
NE'(T
ON
NEXT
RD
PULSE
AD
PULSE
POLLING
A HIGH ENABLES THE
NEXT
Fib
PULSE
TO
READ THE BCD CODe
OF
THE HIGH
EST
LEVEL
REQUESTING INTERRUPT
SPECIAL MASK
MODe
0
1
,
0
,
0
I
0
,
,
RESET
SET
NO
ACTION
SPECIAL
SPECIAL
MA""
MASK
Operation Command Word Format
9-47