View source for DMV11 Synchronous Controller

The '''DMV11 Synchronous Controller''' (more fully, the '''DMV11  Intelligent Communications Synchronous Line Controller''') is a multi-line [[synchronous serial line]] [[peripheral|interface]] for the [[QBUS]]. It used  [[Direct Memory Access|DMA]] to transfer data. It could operate in either [[half-duplex]] or [[full-duplex]], at [[baud rate]]s up to 56K bits/second (depending on [[software]] and system configuration), and supported both point-point and multi-point operation.

The [[byte]]-oriented [[DDCMP]] line [[protocol]] was supported; a [[microprocessor]] is used to implement the protocol.

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The DMV11 used [[Universal Synchronous Receiver/Transmitter]] (USRT) [[integrated circuit|chip]] to implement the  , [[BISYNC]]) and [[bit]]-oriented (e.g. [[SDLC]], [[HDLC]]) protocols were supported. (BISYNC support does not include some aspects, such as [[cyclic redundancy check|CRC]] generation and checking.) The [[character]] length was [[program]]-selectable to 5-8 [[bit]]s (byte-oriented protocols) or 1-8 bits (bit-oriented). A variety of CRC algorithms were supported for error detection; the appropriate one could be selected depending on the protocol in use on the line.

The [[sync character]] was selectable under [[program control]]; the DPV11 could also be set to discard additional incoming sync characters in byte-oriented protocols. In character-oriented mode, it supported idling by sending the sync character; the line could also be set to a [[serial line|mark]] condition when not transmitting characters. In bit-oriented mode, either  abort or flag characters and it was double-[[buffer]]ed for both input and output

It was intended to interface to Bell 200 series [[modem]]s (models 201, 208 and 209) and equivalents. It supported both [[EIA RS-232 serial line interface‎|RS-232]] and [[EIA RS-422 serial line interface‎|RS-422]] interface specifications; it had a complete set of modem control leads, and full modem control under program control. Local loopback for [[diagnostic]]] purposes could be set under program control; remote loopback as well, when a configuration [[jumper]] enabled setting it. 
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It was a [[DEC card form factor|quad]] card; [[Berg connector|Berg headers]] on the card connected to [[flat cable]]s which led off to the modem connectors. There were 4 models, the -AP, -BP, and -FP used the M8053 card, and the -CP used the M8064. (Earlier, there were 3 models; the -AA, -AB, and -AC.)  They supported the following interface standards:

{| class="wikitable"
! Model !! Interface
|-
| -AP || [[EIA RS-232 serial line interface|EIA RS-232C]]/CCITT V.28
|-
| -BP || CCITT V.35
|-
| -CP || Integral modem
|-
| -FP || [[RS-423|EIA RS-423A]]/CCITT V.24
|}

==Registers==

{| border=1
! Register !! Abbreviation !! Address
|-
|Control and Status Register        || SEL0 || 16xxx0
|-
|Control/Response Code Register     || BSEL2 || 16xxx2
|-
|Tributary Address                  || BSEL3 || 16xxx3
|-
|Command/Response Register          || SEL4 || 16xxx4
|-
|Command/Response Register          || SEL6 || 16xxx6
|}

[[Address]]es are assigned from the [[floating device address space]].

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==See also==

* [[DUV11 Line Interface]]
* [[DPV11 synchronous serial line interface]]

==External links==

* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/EK-DMVQM-UG-001%20QMA%20DMV11%20Synchronous%20Controller%20User's%20Guide.pdf EK-DMVQM-UG-001 QMA DMV11 Synchronous Controller  User's Guide]
* [http://www.bitsavers.org/pdf/dec/qbus/EK-DMV11-TM-001_DMV11_Synchronous_Controller_Technical_Manual_Sep81.pdf EK-DMV11-TM-001 DMV11 Synchronous Controller Technical Manual]

[[Category: QBUS Synchronous Serial Interfaces]]