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System Specification for C65Fred BowenMarch 1, 1991

CRC (1XE):
BIT Bit Name Function
0 STARTC 1=START TIMER C, 0=STOP TIMER C. This bit is automatically reset when TIMER C underflow, occurs during one shot mode.
1 PRD6 ON 1=TIMER C output appears on PRD6, 0=PRD6 normal port operation.
2 OUT-C MODE 1=TOGGLE output applied on port PRD6,
0=PULSE output applied on port PRD6.
3 RUN-C MODE 1=ONE-SHOT TIMER C operation,
0=CONTINUOUS TIMER C operation.
4 LOADC 1=FORCE LOAD on TIMER C (this is a STROBE input, there is no data storage, bit 4 will always read back a zero and writing a zero has no effect).
5 TMRC INMODE 1=TIMER C counts positive CNTB transitions,
0=TIMER C counts internal C1MHZ pulses.
6 SPB MODE 1=SERIAL B PORT output mode (CNTB sources shift clock),
0=SERIAL B PORT input mode (external shift clock on CNTB)
7 TODB IN 1=50 Hz operation. C7MHZ divided down by 101339 to generate TODB input of 10 Hz.
0=60 Hz operation. C7MHZ divided down by 102273 to generate TODB input of 10 Hz

CRD (1XF):
BIT Bit Name Function
(Bits 0-4 of the CRD register operate identically to bits 0-4 of the CRD register, except that functions now apply to TIMER D and bit I control's the output of TIMER D on PRD7).
5,6 TIMERD
INMODE
Bits 5 and 6 select one of four input modes for TIMER D as follows:
CRD6 CRD5
0 0 TIMER D counts C1MHz pulses.
0 1 TIMER D counts positive CNTB transitions.
1 0 TIMER D counts TIMERC underflow pulses.
1 1 TIMER D counts TIMERC underflows while CNTB is high.
7 ALARM TODB 1=writing to TODB registezs sets ALARM,
0=writing to TODB registers sets TODA clock.



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