Brother 1250 service manual Main PCB, Asic HL-1030/1240

CHAPTER 3 THEORY OF OPERATION

1.3Main PCB

For the entire circuit diagram of the main PCB, see Appendix 11 to 17.

1.3.1ASIC

HL-1030/1240

A Fujitsu 32bit RISC CPU, MB86833 (SPARC lite) is built in the ASIC. While the CPU is driven with a clock frequency of 33 MHz in the user logic block, it itself runs at 66 MHz, which is generated by multiplying the source clock by two.

The functions of the interface block communication with external devices are described below;

(1)IEEE1284

Stores the data received from the PC into DRAM as controlled by the DMA controller. It is applicable to both normal receiving and bi-directional communication (nibble mode, byte mode, ECP mode).

(2)USB interface (for HL-1240 only)

Stores the data received from the PC into DRAM as controlled by the DMA controller. The transmission speed is 12Mbps.

(3)Engine GA transfer circuit

Communicates with the engine GA by a full-duplex synchronous serial method. The communication speed is 2Mbps.

Fig. 3-7

3-7