CD1865 Datasheet, PDF (124/150 Pages) Intel Corporation – Intelligent Eight-Channel Communications Controller

CD1865 — Intelligent Eight-Channel Communications Controller
9.4.16
Modem Change Option Register 1
Register Name: MCOR1
Register Description: Modem Change Option Register 1
Default Value: 0
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
DSRzd
CDzd
CTSzd
0
Bit 3
DTRth3
Bit 2
DTRth2
8-Bit Hex Address: $10
Intel Hex Address: $20
Motorola Hex Address: $21
Bit 1
Bit 0
DTRth1
DTRth0
This register is used to define the current state change options to be monitored.
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Description
DSRzd is a ‘1’: Detect high-to-low voltage transition on DSR* Input (zero-to-one transition of DSR (MSVR)
bit).
CDzd is a ‘1’: Detect high-to-low voltage transition on CD* Input (zero-to-one transition of CD (MSVR) bit).
CTSzd is a ‘1’: Detect high-to-low voltage transition on CTS* Input (zero-to-one transition of CTS (MSVR)
bit).
Must be a ‘0’.
Defines the threshold level that causes negation of DTR* when this flow-control option is specified. Normally,
this level should be equal to or higher than the service-request level threshold as set in COR3. If it is set lower
than the service-request threshold, it defaults to the service-request threshold level.
Bits 3:0
DTRth3
0
0
0
0
0
0
0
0
1
DTRth2
0
0
0
0
1
1
1
1
0
DTRth1
0
0
1
1
0
0
1
1
0
DTRth0
0
1
0
1
0
1
0
1
0
Function
Automatic DTR mode disabled
1 character
2 character
3 character
4 character
5 character
6 character
7 character
8 character
124
Datasheet