Brother HL 1240 - B/W Laser Printer Service Manual page 42

CHAPTER 3 THEORY OF OPERATION
HL-1250
Fig. 3-4 shows the block diagram of the main PCB of the HL-1250 printer.
Reset Circuit
Program + Font ROM
4.0 Mbytes
RAM
(4.0 Mbytes)
Option RAM (SIMM)
(max. 32Mbytes)
Option Serial I/O
(RS232C & RS422A)
EEPROM (512 x 8 bits)
CPU Core
(MB86832)
BUS
INT
To Engine PCB
Fig. 3-4
3-4
A S I C
Oscillator (32.7MHz)
Address Decoder
DRAM Control
Timer
FIFO
CDCC Parallel I/O
USB I/O
Soft Support
EEPROM I/O
Engine Control I/O
To PC
To PC