View source for DF11 Communications Line Adapter

[[Image:M594.jpg|250px|thumb|right|M594 DF11-A TTL to EIA Level Converter]]

The '''DF11 Communications Line Adapter''' performs two functions for [[serial line]] communication [[interface]]s on [[PDP-11]] computers: i) converts from [[transistor-transistor logic|TTL]] signal levels to the [[voltage]]s, etc needed by a given serial line standard, and ii) produces the physical connector needed for that standard.

A DF11 usually involves two [[DEC card form factor|single-width]] cards, one holding the circuitry needed, and the other providing, sometimes with a cable plugged into a [[Berg connector]], the interface connector. At least one dual-width adapter (the DF11-B) existed, though.

The DF11 plugs into a common [[backplane]] with the serial interface. DF11's are used with [[DP11-A synchronous serial line interface|DP11]], [[DM11 asynchronous serial line interface|DM11]], [[DH11 asynchronous serial line interface|DH11]], [[DC11 asynchronous serial line interface|DC11]]; and [[DL11 asynchronous serial line interface|DL11]] and [[DU11 synchronous serial line interface|DU11]] [[UNIBUS]] serial interfaces (the latter two only in [[DD11-B backplane]]s, where the DF11 plugs into the A-B [[DEC edge connector contact identification|connectors]]). They may also be used in some versions of the [[PDP-11/05]] or [[PDP-11/10]].

DF11 models include:

* DF11-A (M594, M957-BC01R, M970-BC01R for modem cable) - [[EIA RS-232 serial line interface|EIA RS-232]] adapter
* DF11-BA (M586) - integral [[modem]] for connection to a telephone line
* DF11-BB (M587) - integral answer-only modem
* DF11-F (M596, M973) - [[20mA current loop serial line interface|20m current loop]] adapter; '[[active]]' mode (up to 300 [[baud rate|baud]])
* DF11-G (M595, BC01T-BC01Y) - custom 20mA interface to a Bell 301/303 modem
* DF11-K (M598, M973) - 4-wire opto-isolated 20mA adapter; '[[passive]]' mode (up to 2400 baud)

The DF11-K has [[jumper]]s to allow each channel to be changed to [[20mA current loop serial line interface|'active']] mode.

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==External links==

* [http://www.bitsavers.org/pdf/dec/pdp10/periph/MP00068_DN87_Universal_Comm_System_Front_End_Jan76.pdf DN87 Field Maintenance Print Set] - contains complete engineering drawings for the DF11 boards on pp. 73-99

[[Category: UNIBUS Serial Interfaces]]