DC11 asynchronous serial line interface
The DC11 asynchronous serial line interface is an early UNIBUS peripheral which provides an asynchronous serial line connection to a modem (Bell 103 and 202 models), using an EIA RS-232 interface. Both input and output used programmed I/O (with separate receive and transmit interrupts); there was no buffering.
The line parameters:
- baud rates (4 speeds, separate for transmit and receive, ranging from 50 to 1800, depending on the clock module )
- character length (5-8 bits)
- output stop bits (1 or 2)
- input parity (even or odd)
could be set under program control. A 'break' condition on the line (i.e. continuous assertion) could also be generated and detected.
The speeds available with various models were:
|-AA||300, 150, 134.5, 110|
|-AB||1800, 1200, 300, 110|
|-AC||1200, 600, 150, 110|
|-AD||150, 134.5, 110, 50|
|-AE||150, 134.5, 110, 75|
|-AG||1200, 300, 150, 134.5|
|-AH||1800, 1200, 134.5, 110|
|-AX||Other (up to 19.6K), 150, 134.5, 110|
Other DF11 Communications Line Adapters could be used in place of the EIA RS-232 interface card.
|Receive Status Register||DCRCSR||774000|
|Receive Buffer Regist||DCRBUF||774002|
|Transmit Status Register||DCTCSR||774004|
|Transmit Buffer Register||DCTBUF||774006|
The addresses shown are for the first DC11 in a system; additional ones (up to 32 total) are normally set to be at 774010, 774020, etc to 774370.
- M794 Interface (quad)
- M7821 - Interrupt control
- M105 - Address selection
- M594 EIA level converter
- M957 data set cable connector
|2||G8000 filter||M454 clock||M794|
@ = M205 for -AD, -AE; M405 for -AX; or blank