Oki ML490 Maintenance Manual - Page 11
Program ROM
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(2) Program ROM This is a 512K × 16 bits (8M bit) [MAX 16M bit] OTPROM or MASK ROM with the control program for the printer stored. The MPU executes instructions under this program. The program ROM is assigned to the program memory area of the MPU and is fetched by the PSEN-N signal of the MPU. The following shows the operation of the memory access. MPU CSO PSEN A0~A18 D0~D15 PG-N PSEN-N Program ROM CE OE MPU CLOCK A0~A18 PG-N PSEN-N D0~D15 42114101 Rev.1 11 /
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42114101
Rev.1
11 /
MPU CLOCK
A0~A18
PG-N
PSEN-N
D0~D15
CSO
PSEN
CE
OE
PG-N
PSEN-N
D0~D15
A0~A18
MPU
Program ROM
(2)
Program ROM
This is a 512K
×
16 bits (8M bit) [MAX 16M bit] OTPROM or MASK ROM with the control
program for the printer stored. The MPU executes instructions under this program.
The program ROM is assigned to the program memory area of the MPU and is fetched
by the PSEN-N signal of the MPU.
The following shows the operation of the memory access.