R46 Circuit Diagram (4/15) - Oki OKIFAX4550 Maintenance Manual

4.2

R46 Circuit Diagram (4/15)

1. Block diagram
R46-PCB circuit diagram (4/15) shown the consists of Flash memory, DRAM, Real time clock
IC and Back up battery circuit.
Figure A.20 shows the block diagram of Flash memory, DRAM and Real time clock.
2. Function
1) Flash memory (FLS1)
Flash memory (electrically erasable and programmable device) is used for the main
software program, which is stored in EP-ROM of the current OKIFAX. Other than the
function of EP-ROM, Flash memory is also used for the user data area instead of SRAM
chips.
• 1M Byte Flash memory × 1 (FLS1)
Used for work area, report recording etc.
2) DRAM
RAM1: 8MB (2k words × 16 bit)
• Used as follows:
Picture memory for the ECM send/receive mode.
Picture memory for the memory transmission mode.
Picture memory for the retransmission mode.
Picture memory for the reception in memory.
Editing for report printing.
3) Back-up battery circuit
The non-rechargable lithium battery supplies voltage to a real-time clock IC at AC main
interruption.
4) Real-time clock IC (IC22)
A real-time clock IC (serial I/F) incorporating a crystal osillator is used. Its basic frequency
is 500 Hz. IC2 pins 217 (RTCCS), 216 (RTCWR), 215 (RTCDATA), and 214 (RTCCLK)
are used as I/F signal pins.
The drive voltage is 3V and backup by a dedicated lithium battery.
NCASH0/NCASL0
NRD3/NWR3
RTCWR/CS
Figure A.20 Block Diagram of DRAM/Flash Memory and Real-time Clock IC
41309401TH Rev.4
A1 to A19
RTCCK
Flash
memory
1MB (×16)
RAM1
8MB (×16)
IC22
Real time
clock IC
DT0 to DT15
RTCDATA
332 /