Circuit Description; Memory Map; Memory Protection - Sharp ZQ-5000 Service Manual

ZQ-5000
When input voltage VIN exceeds the detection voltage VD, the output
of the voltage detection IC [LBIC (MN1280)] is driven from Low to
High. When VIN falls under VD, the output is driven from High to Low.
The LBIC (MN1 280) detects both the CAU level and the STOP level
by dividing the voltage applied to the input terminal (2 pin) with Rl
and R2 and by turning on/off R2 with CAU signal of G-A.
When the power voltage falls under the CAU level, as shown in Fig.
3, the BAl7 symbol lights up. When the power voltage falls further
under the STOP level, the symbol goes off.
For CAU level detection, the CPU E9 terminal it turned on (low level)
and the CPU IRQ terminal state is observed. (If the IRQ is at Low
level, the symbol lights up.)
When the CAU level is detected, the CPU E9 terminal is turned off
(high impedance). (When the CPU E9 terminal is turned off, resistor
division is not performed and the voltage at LBIC 2 pin increases,
driving the output from Low to High.) The CPU IRQ terminal state is
checked again to detect the STOP level.
After the STOP level is detected, the ON key and the RESET key
become ineffective.
4
CPU E9
Backup
After Smsec of E8' s becoming high, DIS becomes low. After I oopsec,
the back-up battery low voltage is detected. When LBIC is high, it is
normal. When LBIC is low, KIO becomes high to turn off the display
of <ATTENTION> after 5 sec.

6. Memory map

DRIVER
l o o o o t
2oooot
EX RAM1
3oooot
EX RAM2
4oooot
EX CED
256 KS
CEO
EX CED
CE3
c o o o o t
CE4
SYSTEM ROM
1 MB
04000H
07FFFH