Epson LQ-2550 Technical Manual page 88

The main functions of the main CPU and its peripheral components are as follows:
Interfacing with the host computer
Processing and expanding the commands and data input from the computer via the interface
Printhead control
The main CPU controls the memory using a gate array (MMU: 14A).
Figure 2-34 shows the IC address map for the main CPU.
The main functions of the sub CPU and its peripheral components are as follows:
Printer mechanism control
Control panel control
Printer cover state monitoring
Buzzer driving
The sub CPU has a multiplexed low order address/data bus. The low order address bus and data bus
are selected according to the ALE signal from the sub CPU via a latch ( 14C).
Figure 2-35 shows the IC address map for the sub CPU.
( 14)
FDAOH
LS375
( 14C)
FD40H
E05A02LA
( 2 A )
G/A
FD20H
FDOOH
PS RAM
( 9 A )
BANK AREA
6000H
PROGRAM ROM
( 1 1A)
PS-RAM (9A)
I
1 Kbyle X 32 BANK
(C GO. 12A)
40H
BANK ADDRESS ~
Figure 2-34. Main CPU Address Map
I I
SLOT 256 Ki~~f)TRAM
Not used
Figure 2-35.
2-41
INTERNAL RAM
FFOOH
MCU G/A
( 3 B )
COOOH
MCU G/A
(4 B)
I
I
PROGRAM ROM
m
Sub CPU Address Map