Service manual

58
8575
8575
A N/B Maintenance
A N/B Maintenance
SM BUS clock need pull high 5→3VKeepI/OI/OI/OT↑BAT DATA16P97/WAIT/SDA
Read H8 send A20gate statusTIIIT↑ENABKL17P96/0
need pull highKeepI/OI/OI/OT↑H8/T DATA18P95/AS
need pull highKeepI/OI/OI/OT↑M DATA19P94/WR
need pull highKeepI/OI/OI/OT↑K/M DATA22P93/RD
need pull high
SM BUS clock need pull high 5→3V
CPU A20gate
KeepI/OI/OI/OT↑K/M CLK25P90/IRQ2/ESC2
Port 9 TTL input voltage (input high min=2V, input low max=0.8V)
KeepIIITISA SA293P80/HA0
need pull high
need pull high
IO port 62/66 chip select
ISA I/O write
ISA I/O read#
IO port 60/64 chip select
Function
Keep
Keep
Keep
Keep
Keep
Keep
Keep
Keep H
STANDBY
I/O
I/O
I/O
I
I
I
I
O
I/O
I/O
I/O
I
I
I
I
O
ON
I/O
I/O
I/O
I
I
I
I
O
After
RESET/OFF
T↑
T↑
T↑
T
T
T
T
T
During
RESET
H8/T CLK
M CLK
BAT CLK
H8 MCCS#
ISA IOW#
ISA IOR#
H8 KBCS#
X(H8 A20GATE)
H8 Pin
Definitions
23
24
99
98
97
96
95
94
Pin
P92/IRQ0
P91/IRQ1/EIOW
P86/IRQ5/SCK1
P85/IRQ4/RXD1
P84/IRQ2/TXD1
P83/IOR
P82/CS1
P81/GA20
Port 8 TTL input voltage (input high min=2V, input low max=0.8V)
Name
↑ Pull High
↓ Pull Low
5→3V Level shift
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