Oki B 4100 Maintenance Manual page 405

A3.2.3 M17 Circuit Diagram (Page 3/17)
1. Block diagram
The circuit diagram shown on page 3/17 consists of Flash memory, Mask ROM, IC3 (Real time
clock IC) and Back up battery circuit.
Figure A3.2.3 shows the block diagram of Flash memory, Mask ROM and Real time clock.
2. Function
1) Flash memory (FLS)
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.
• 512 KByte Flash memory x 1 (FLS)
2) Back-up battery circuit
• Non-rechargeable lithium for RTC-IC (real-time clock IC)
3) Real-time clock IC (IC3)
IC3 is a real-time clock IC used as a timepiece to display the data and time in year, month,
day, hour, minute, and second units. Its input/output signals are the 4-bit data bus (AD00 -
AD03), 4-bit address bus (A01 - A04) and the control signals PRDY0, RTCCS, MDMRD-
N and RTCWR-N which perform a CPU-controlled read operation (M/D/Y H:M, Data
read) and write operation (M/D/Y H:M, Data setting).
4) MASK
• 512 KByte Flash memory or Mask ROM x 1 (MASK)
A0 to A18
RMCS1-N/
RMCS0-N
+24V
F12VON
MDRD-N/
MDWR-N
Figure A3.2.3 Block Diagram of FLS, MASK and Real Time Clock
40055101TH Rev.4
Used for work area, report recording etc.
Used for program storage
RP/VPP
circuit
A0 to A3
X2
32.768KHz
MASK
FLS
AD0 to
AD3
IC3
Back-up
battery
circuit
AD0 to AD15
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