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REV.-A
Pin No.
Signal Name
In/Out
Function
- -
33
INT 1
In
Serial controller 82C51 interrupt signal
- -
34
INT5
In
Interrupt signal from option unit
35
N/C
-
Not used.
36
SCK
In
Data transmit/receive shift clock against
SIOR register. Provided from sub-CPU 7508.
- -
37
INT2
In
RS-232C CD signal interrupt signal
-
38
RD
In
Read signal: Synchronized to AND of IORO.
Outputs data on data bus.
39
AB1
In
Address bus 1
-
40
WR
In
Write signal: Synchronized to AND of IORO.
Outputs data on data bus.
41
INTS
Out
Interrupt signal to sub-CPU 7508
42
ABO
In
Address bus 0
43
RDY
In
Ready signal of sub-CPU
44
LED 2
Out
Lamp control signal of LED on keyboard
(lowest of the three)
45
AB 7
In
Address bus 7
46
LED 1
Out
Lamp control signal of LED on keyboard
(highest of the three)
47
LEDO
Out
Lamp control signal of LED on keyboard
(center of the three)
- -
48
IORO
In
Main CPU in MI cycle: Request to output in-
terrupt response vec-
tor on data bus.
49
AB2
In
Address bus 2
- -
50
CSOC
Out
Serial controller 82C51 chip select signal.
51
BANKOj1
Out
Bank select signal
-
52
M1
In
Main CPU in machine cycle 1 :
Interrupt response vector is read to main
CPU by AND operation with IORO.
53
N/C
-
Not used.
7-27
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