Sharp PC-1600, Service Manual, Page: 30 / 118

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PC-1600
9-3.
Sub CPU (LU57813P) pin description
Pin
Symbol ln/Out
Active State
Function
No. level at ACL
1
QO In Low In When the system-off command is received from the Z-80, the svstern is
turned off after this signal goes low. It has PCTR L output from the SC7852
as its input.
2 VDD
High side VGG is supplied.
3 ACL In High
The pulse width of ACL must be greater than 1 microsecond in duration to be
recognized by the hardware. It takes about 80 microseconds before the LSI
starts to operate after input of ACL. This pin is used as reset input from the
ALL RESET switch of the PC-1600.
4
CL1
In The svstern clock generating ceramic oscillator is attached across these two
5 CL2 Out
lines. With the PC-1600, a 1.229MHz oscillator is used for the basic clock of
the RS-232C baud rate.
6 FOUT Out
System clock outpur. Not used.
7
PO
Out Low
In Reset input to the SC7852.
This line is maintained low for 30 milliseconds during system-on and reset.
8
Pl Out Low In In a low state when the main CPU is permitted to accessthe memory and
1/0.
9
P2
Out
High In In an opposite level of P1. Input to SLCT of the SC7852.
10 P3 Out Low In In a low state during system-on.
Used to turn on the system.
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11 KH In
High
This signal goes high with an input of the ON key. When the system is off,
this LSI is in the standby mode, and it turns on the system with a high KH
state.
12 KI In High A command request from the main CPU. lnterrupt is caused by a high K1
state.
13 T In Test pin which is NC.
14
OSCOUT Out The 32.768 KHz timer crvstal oscillator is attached across these lines.
15 OSCIN In
16 KL In High Reset input from the peripheral unit. As monitored by the software, if this
input is high for more than the given.time, the reset is executed.
17
Z15 Out High In Z15 and KL are shorted outside and externally pulled down by the resistor.
Z15 is turned high for 1 millisecond in the reset routine to be converted
into the RSTE signal, and sent to peripherals as the reset signal via the
system bus. So, both Z15 and KL can be handled as an input/output line,
which may be used to apply reset to the peripheral or to receive reset from
the peripheral. This signal is used as the reset input of the CE-1600P.
18 Z14 Out High In The sub CPU monitors the state of the BREAK/ON key via the KH input
line and its state is sent through Z 14 and supplied to PB7 of the SC7852.
Therefore, key chattering and bouncing of the BREAK/ON key are corn-
pletely controlled the sub CPU.
19 Z13 Out Low In The sub CPU goes into the power-down mode except when one of the
conditions mentioned below holds true.
(1)
When a command is received from the main CPU.
(2) When a timer interrupt is received.
(3) If the BREAK/ON key sensing KH input is at a high level.
To prevent these conditions from occurring, Z 13 is set low at every time
interrupt (1/128 second). If KH is at a high level, depression of the
BREAK/ON key is sensed.
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