SCD1284 INTEL [Intel Corporation], SCD1284 Datasheet - Page 132

• Manufacturer Part Number: SCD1284
• Description: IEEE 1284-Compatible Parallel Interface Controller with Two High-Speed Asynchronous Serial Ports
• Manufacturer: INTEL [Intel Corporation]

CD1284 — IEEE 1284-Compatible Parallel Interface Controller
7.5.7
132
Register Name: RDCR
Register Description: Received Data Count
Access: Read only
Bit 7
0
Bit
7:4
3:0
Received Data Count Register
The RDCR indicates the number of good characters currently in the serial received data FIFO. Host
software can use this value as a loop counter when taking characters out of the FIFO. The value in
this register is only valid during the context of a service request acknowledge. At other times, it
may or may not give a true indication of the number of characters in the FIFO.
These bits must always be ‘0’.
Character Count 3:0: The encoding for these bits is:
Bit 6
0
ClkSel2
CT3
0
0
0
1
1
1
1
1
•
1
1
1
CT2
Bit 5
0
0
0
0
1
1
1
1
•
0
ClkSel1
0
1
1
CT1
0
0
1
1
0
0
1
1
•
Bit 4
0
CT0
0
1
0
1
0
1
0
1
ClkSel0
•
1
0
1
Description
Bit 3
CT3
Not used.
1 character
2 characters
11 characters
12 characters
Not used.
Not used.
Number of characters in FIFO
Bit 2
CT2
Clock Selected
Bit 1
CT1
8-Bit Hex Address: 0E
Default Value: 00
Datasheet
Bit 0
CT0