DLV11-J asynchronous serial line interface

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The DLV11-J asynchronous serial line interface card (M8043) was a QBUS peripheral for the PDP-11 series of computers which provided four asynchronous serial lines on a single dual-width card.

It provided both EIA RS-232 or RS-422 connectivity at speeds of 150 to 38.4K baud; receive and transmit speeds are the same on each line, but each line could be set independently. It did not have any modem control.

Line connection was via 10-pin Berg connector headers on the top edge of the card, using the standard DEC asynchronous serial line pinout.

Programing interface

Like the ancestral KL11, for each line the DL11-J has 2 device registers for the receive side (one Control and Status Register - CSR - and one data buffer register), and similarly, two for the transmit side. Each line has two interrupt vectors - again, one receive, and one transmit.

Normally both the registers and interrupt vectors are in contiguous blocks for the 4 lines, but there are special provisions for one line to be configured as the PDP-11 main console (which is always a KL11/DL11 compatible device). The standard there is that 0777560 is the base address (so the receiver registers are 0777560-2, and the transmitter are 0777564-6), and 060 is the base vector.

That line can be set to halt the CPU, or re-boot the system, when a 'break' is seen. All lines can send a 'break'.

The first line after the console is always assigned the address 0776500, and vector 0300. Additional lines are assigned addresses and vectors immediately following, for DL11's #1-#16 (i.e. 0776500-676 and 0300-0476).

See also