Panasonic KX-FT907BX-B Service Manual page 110

KX-FT907BX-B / KX-FT907BX-W
8.3.3. ROM (IC2)
This 512 KB ROM (OTPROM or MASKROM) has 32 KB of common area and bank area (BK4~BK 63).
The capacity of each bank is 8 KB.
The addresses of the common area are from 0000H to 7FFFH, and addresses 8000H to 9FFFH are for the bank area.
8.3.4. RAM (IC4)
This 128 KB RAM has 8 KB of common area and bank area (BK0, BK1).
The capacity of each bank is 12 KB.
The addresses of the common area are from D000H to EFFFH, and addresses A000H to CFFFH are for the bank area.
8.3.5. RESET CIRCUIT (WATCH DOG TIMER)
The output signal (reset) from pin 4 of the voltage detect IC (IC3) is input to the ASIC (IC1) 114 pin.
1. During a momentary power interruption, a negative reset pulse of 50~70 msec is generated and the system is reset completely.
2. The watch dog timer, built-in the ASIC (IC1), is initialized by the CPU about every 1.5 ms.
When a watch dog error occurs, pin 115 of the ASIC (IC1) becomes low level.
The terminal of the ´WDERR´ signal is connected to the reset line, so the ´WDERR´ signal works as the reset signal.
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