Motorola MC68306 User Manual page 143

OP bits 7, 6, 5, 4, and 2 are not pinned out on the MC68306;
thus changing bits 7, 6, 5, 4, 1, and 0 of this register has no
effect.
OPCR3–OPCR2—Output Port 3 Function Select
00 = OPR bit 3
01 = Counter/timer output
10 = TxCB (1X)
11 = RxCB (1X)
OP3 is open-drain in this mode, and an external pullup is
required.
OPCR1–OPCR0—Output Port 2 Function Select
00 = OPR bit 2
01 = TxCA (16X)
10 = TxCA (1X)
11 = RxCA (1X)
MOTOROLA
DUOPCR
7 6 5
OP7 OP6 OP5 OP4
T≈RDYB T≈RDYA R≈RDYB R≈RDYA
RESET:
0 0 0
Write Only
MC68306 USER'S MANUAL
4 3 2 1
OP3 OP2
0 0 0 0
NOTE
NOTE
0
0
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