CD1865 Datasheet, PDF (123/150 Pages) Intel Corporation – Intelligent Eight-Channel Communications Controller

Intelligent Eight-Channel Communications Controller — CD1865
9.4.14
Special Character Register 4
Register Name: SCHR4
Register Description: Special Character Register 4
Default Value: 0
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Special Character 4
Bit 2
8-Bit Hex Address: $0C
Intel Hex Address: $18
Motorola Hex Address: $19
Bit 1
Bit 0
9.4.15
This register stores the right-justified bit pattern for Special Character 4. Unused bits must be a ‘0’.
During receive, this character is one of the four characters compared with the received data for
special character recognition. If a match occurs with one of these four characters, it is noted in the
Receiver Status FIFO entry accompanying the received character unless a double-character
compare is enabled. In this case, the Receive Status FIFO entry is not made until both characters
are compared.
During transmit, this register contains the characters that are sent as a result of the Send Special
Character 4 command.
Special Character 4 may be the second-half of the Xoff-character sequence.
Modem Change Register
Register Name: MCR
Register Description: Modem Change Register
Default Value: 0
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
DSRchg
CDchg
CTSchg
0
Bit 3
0
Bit 2
0
8-Bit Hex Address: $12
Intel Hex Address: $24
Motorola Hex Address: $25
Bit 1
Bit 0
0
0
The CD1865 sets bits in this register when it recognizes a level change on a modem pin, as
programmed by the Modem Change Option registers. Changes detected are a cause for asserting
the Modem Service Request if corresponding Service Request Enable bits are set. Once the service
request is asserted, updates to this register are inhibited until End Of register () is written at the end
of the Modem Service Request Routine. The host must clear these register bits during the service
routine.
Bit
Bit 7
Bit 6
Bit 5
Bits 4:0
Description
DSR Changed: A logic ‘1’ denotes that the Data-Set-Ready Input has changed state.
CD Changed: A logic ‘1’ denotes that the Carrier Detect Input has changed state.
CTS Changed: A logic ‘1’ denotes that the Clear-to-Send Input has changed state.
Must be a ‘0’.
Datasheet
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