Oki PACEMARK 4410, Service Manual, Page: 14 / 215

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(2) PG ROM (IC46)
This is a 256 x16 bits (4M bit) EPROM 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
RD signal of the MPU.
The following shows the operation of the memory access.
Figure 2.2
MPU CLOCK
ALE
A16~BHE
AD0~AD15
RD
CS
AD0~AD15
A16~BHE
MPU
Main LSI CG ROM
NHDC LSI
A16-BHE
A0–A15 D0–D15
ALE
RD
WR
CS
CLK
BANK0
BANKS
CS
A17
A16
A0~A15
OE
CE
A1~A16