(2)Program ROM
This is a 256 × 16 bits (4M bit) [MAX] 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 PSEN signal of the MPU.
The following shows the operation of the memory access.
MPU CLOCK
A0~A17
D0~D15
MPU | ROM |
| A0~A17 |
| D0~D15 |
| |
CSO | CE |
PSEN | OE |
Program | Program | Program |
IN | IN | IN |
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