Brother International HL-1070 Service Manual - Page 22

(7) Parallel I/O There are two modes in this unit. One is the CPU receive mode and the other is the DMA receive mode. In the CPU receive mode the CPU receives the command data from the PC, and after the CPU is switched to the DMA mode, it receives the image data and writes it to the DRAM directly. CPU Receive Mode STROBE BUSY ACK 90 µsec 0.5 µsec DMA Receive Mode STROBE BUSY ACK 1.5 µsec 0.5 µsec BUSY goes HIGH at the falling edge of the STROBE signal. The data (8 bits) from the PC is latched into the data buffer at the rising edge of the STROBE signal. The pulse width of ACK varies according to the speed MODE as shown above. BUSY goes LOW on the rising edge of ACK. This supports the IEEE1284 data transfer with the following mode. Nibble Byte ECP mode mode mode (8) Data extension This circuit extents the compressed image data which are received from the PC, and writes the bit map data to the FIFO. (9) Software support Supports 16 x 16 rotation, bit expansion, bit search, and decimal point conversion. (10) EEPROM I/O One output port and one I/O port are assigned. II-6