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4.7.2 SMC Programming Model
The operating mode of both SMC ports is defined by SMC mode, which
consists of the lower eight bits of SPMODE; As previously mentioned, the
upper eight bits program the SCP.
5
4
3
2
1
0
- I - I
SM02
I
SMD1
I
SMDO
I
LOOP
I
EN2
I
EN1
Bits 7-6 - These bits are reserved and should be set to zero.
SMD2-SMDO- SMC Mode Support
000 = GCI - The monitor channel is not used.
001 = GCI - The monitor channel data and the A and E control bits are
received and transmitted transparently by the IMP.
01 X = GCI - The monitor channel data and the A and E control bits are
internally controlled according to the monitor channel pro-
tocol.
100 = IDL - The M and A channels are in hunt-on-zero mode.
101 = IDL - Only the M channel is in hunt-on-zero mode.
110 = IDL - Only the A qhannel is in hunt-on-zero mode.
111 = IDL - Regular operation; no channel is in hunt-on-zero mode.
LOOP - Local Loopback Mode
0 =Normal mode
1 =Local loopback mode
EN2 - SMC2 Enable
0 =Disable SMC2
1 =Enable SMC2
EN1 - SMC1 Enable
0 =Disable SMC1
1 =Enable SMC1
4. 7.3 SMC Commands
The following commands issued to the CP command register (see 4.3 COM-
MAND SET) are used only when GCI is selected for the serial channels phys-
ical interface.
MOTOROLA
MC68302 USER'S MANUAL
4-115
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