II-4
1.3.2
ASIC
The ASIC is composed of a Cell Based IC and has the following function blocks.
(1)
Oscillator circuit
Generates the main clock for the CPU by dividing the source clock frequency by
two.
(2)
Address Generator
This controls the address buss by latching the AD buss signals with the ALE
signal.
(3)
Address decoder
Generates the CS for each device.
(4)
DRAM control
Generates the RAS, CAS, WE, OE and MA signals for the DRAM and controls the
memory refresh processing (CAS before RAS self-refreshing method).
(5) Interrupt control
Interrupt levels:
Priority
High
9
TIMER 3 (Watch Dog)
8
MONITOR
7
FIFO
6
EXINT
5
TIMER1
4
BD
3
Spare
2
CDCC / BOISE / DATA EXTENTION
Low
1
TIMER 2
All the interrupts can be masked.
(6)
Timers
The following timers are included:
Timer 1
16-bit timer
Timer 2
10-bit timer
Timer 3
Watch-dog timer
(7)
FIFO
A 10Kbit FIFO is includedrporated. Data for one raster is transferred from the
RAM to the FIFO by DMA transmission and is output as serial video data. The
data cycle is 6.13 Mhz.
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 ...
