II-8
(7) CDCC parallel I/O
<Data receiving>
There are two modes in this unit. One is the CPU receiving mode and the other is
the DMA receiving mode. In the CPU receiving 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 to the DRAM directly.
CPU Receiving Mode
90 µsec
STROBE
BUSY
ACK
STROBE
BUSY
ACK
0.5 µsec
0.5 µsec
1.5 µsec
BUSY goes HIGH at the falling edge of STROBE. The data (8 bits) from the PC is
latched in the data buffer at the rising edge of STROBE. The pulse width of ACK
differs according to the speed MODE as shown above. BUSY goes LOW at the
rising edge of ACK.
<IEEE1284 support>
This supports the IEEE1284 data transfer with the following mode.
Nibble mode
Byte
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) FIFO
A 5,120-bit FIFO is incorporated. Data for one raster is transferred from DRAM to
the FIFO through the data extension unit and exported as the serial video data.
The data cycle is 6.13 MHz.
(10)EEPROM I/O
One output port and one I/O port are assigned.
Summary of Contents for HL-720
Page 1: ...SERVICE MANUAL MODEL HL 720 730 730Plus R LASER PRINTER ...
Page 36: ...II 19 1 3 10 Engine I O HL 720 Fig 2 21 shows the engine interface circuit Fig 2 21 ...
Page 37: ...II 20 HL 730 730Plus Fig 2 22 shows the engine interface circuit Fig 2 22 ...
Page 61: ... Fig 3 18 2 4 1 1 1 ...
Page 92: ...SERVICE MANUAL MODEL HL 760 R LASER PRINTER ...
Page 109: ...II 8 1 3 4 DRAM Two 4M bit DRAMs x 16bits are used as the RAM Fig 2 6 ...
Page 113: ...II 12 1 3 10 Engine I O Fig 2 12 shows the engine interface circuit Fig 2 12 ...
Page 114: ...II 13 1 3 11 Paper Feed Motor Drive Circuit Fig 2 13 ...
Page 133: ...Appendix 2 Main PCB Circuit Diagram 1 3 CODE UK3227000 B48K272CIR 1 3 NAME ...
Page 134: ...Appendix 3 Main PCB Circuit Diagram 2 3 CODE UK3227000 B48K272CIR 2 3 NAME ...
Page 135: ...CODE UK3227000 B48K272CIR 3 3 NAME Appendix 4 Main PCB Circuit Diagram 3 3 ...
