-
PC-l600
Pin
Symbol
ln/Out
Active
Function
No.
level
24
CKOS
In
The 00 signal indicates that the CPU (LH5803) read timing is at a low level when not
writing, So, it may possibly be at a low level when not reading, and it also may not
match the Z-80's timing during data input/output of the SC7852 internal data.
I
To prevent these problerns, the signal goes low only when the LH;5803 is reading the
memory or 1/0 is created with five signal (MEO, ME1, 00, CKOS, and BR05).
25
VCC
-
Power supply (Input of VGG of the system),
26
GNO
-
Power supply.
27
BRQ
In See Pin No. 24.
28-30 00-02
ln/Out
Z-80 data bus.
31-35
03-07
Out When the sub CPU outpur P1 (SLCB), wh ich is sent out when the system is off, is at
a high level, 02- 00 become low, thus fixing the level of the .input sinal during
system-off as 02 - 00 are inputs also.
36
c/5
In
High
The c(B line 01 the SC7852 goes high when the Z-80 wirites 30H of the 1/0.
37
10RP
In Low
The signal used to send R33- R20 on the Z-80 data bus.
It goes low when the Z-80 reads 33H 01 the 1/0.
38 CL
In
Low
System reset input. When this signal is at a low level, it forces A 16A to high, A 15A
to low, and A14A to high.
39
A13 In CPU address A 13.
40
A14
In
Input of the CPU address A14 (insigni1icant).
41
OSR
Out
Not used.
42
CLKl Out When the system is on, CL2 is issued on this line and becomes the basic clock for the
UART. A low is on this line when the system is off.
43
KH
Out
High
Opposite polaritv of the BREAK/ON key Input is sent to the sub CPU.
44 A13A
Out Opposite polarity of the A 13 input is sent.
45-47 A14A-A16A
Out C/O latched 02-00 outpur.
!
Also, A 16A is used for separating the
CS24
selected 16KB memory space 4000H-
7FFFH (bank 3) into two banks.
48-50 LHS1-LHS3 In
Low Memory select and 1/0 select signals from the SC7852 are sent to slots of S1: and
!
51-53 KAO-K2
In
Low
S2: via the gate arrav. The reason why is that it has to be set at a high level at
system-off as the SC7852 power supply is shut off when the system is off.
(1 )
When the system is on but not in a weak battery condition the status of each
signal appears on S1, S2, S3, KO, K1, and K2.
(2)
All are high when the system is off or a weak battery is detected.
54-56 Sl-S3
Out Low LHS1-KA2 outputs,
59-61 KO-K2
Out
Low All are high outputs when the system is off.
62 ME1
In
63 MEO
In See pin NO.24.
64
00
In
-------
--------
-!-\1-
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