View source for DM11 distribution panel

The '''DM11 distribution panel''' (formally, the '''DM11-AA distribution panel) was used with the [[DM11 asynchronous serial line interface|DM11]], and early models of the [[DH11 asynchronous serial line interface|DH11]] interfaces, to connect these [[peripheral|interfaces]] to [[asynchronous serial line]]s which used a number of different low-level electrical interface specifications, and connected either to local [[terminal]]s, or to [[modem]]s.

Both of these devices used a custom [[system unit]] [[backplane]], containing multiple cards; one or more [[flat cable]]s connected this to the backplane of the separate 5-1/4" high rack-mounted [[DEC card form factor|dual-height]] distribution panel.

Modular 'line conditioning' units were installed in the distribution panel's backplane, to allow support of either [[20mA current loop serial line interface|20mA]] serial lines (local only), or [[EIA RS-232 serial line interface|EIA RS-232]] serial lines (local or modems - modems usually required a [[DM11-BB Modem Control Option]] as well as the basic asynchronous serial line interface).

==Line conditioning==

Three broad choice were available for line conditioning:

* Use any unit from the [[DF11 Communications Line Adapter]] series, each of which only supported a single line.
* Use the DM11-DA (20mA line conditioning) or DM11-DB (EIA, no modem control), each of which supported four lines; thus, with these, line conditioning could be mixed in groups of four.
* Use the DM11-DC (EIA, modem control), each of which also supported only one line.

The DM11-DA included:

* M596 - TTL to 20mA Level Converter
* M973 - Mate-N-Lok header (4 per M596)

and in the DM11-DB:

* M594 - TTL to EIA Level Converter
* W404 - DTR Jumper card (4 per M594)

Note that these are all DF11 cards; however, they were plugged into different slots in the DM11 distribution panel backplane from cards used for single lines. (There were slots at the ends of the distribution panel's backplane into which the 4-line cards plugged; a group of 16 slots in the middle could hold the DF11's or DM11-DC's.)

The DM11-DC consisted of four M594s, plugged into individual line slots.

[[Category: UNIBUS Serial Interfaces]]