Epson PX-8 - Page 298

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.
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