DPV11 synchronous serial line interface
The DPV11 is an early synchronous serial line interface for the QBUS for a single line. Like the earlier UNIBUS synchronous serial line interfaces, it used programmed I/O (with separate receive and transmit interrupts) to transfer data, and it was double-buffered for both input and output. It could operate in either half-duplex or full-duplex, at baud rates up to 56K bits/second (depending on software and system configuration).
The DVP11 used a Universal Synchronous Receiver/Transmitter (USRT) chip to implement the line protocol. Both byte-oriented (e.g. DDCMP, BISYNC) and bit-oriented (e.g. SDLC, HDLC) protocols were supported. (BISYNC support does not include some aspects, such as CRC generation and checking.) The character length was program-selectable to 5-8 bits (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 mark condition when not transmitting characters. In bit-oriented mode, either abort or flag characters
It was intended to interface to Bell 200 series modems (models 201, 208 and 209) and equivalents. It supported both RS-232 and 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.
It was a dual card, the M8020; a Berg header on the card connected to a BC26L cable which led off to an EIA connector.
Contents
Registers
| Register | Abbreviation | Address |
|---|---|---|
| Receive Control and Status Register | RCSR | 16xxx0 |
| Receive Data and Status Register (read only) | RDSR | 16xxx2 |
| Parameter Control Sync/Address Register (write only) | PCSAR | 16xxx2 |
| Parameter Control and Character Length Register | PCSCR | 16xxx4 |
| Transmit Data and Status Register | TDSR | 16xxx6 |
Read-only bits are shown in ITALICS; write-only bits are shown in BOLD; read/write bits are in normal font.
16xxx0: Receive Control and Status Register (RCSR)
| DSC | IC | CTS | RR | RACT | RCVST | DMV | SYNFLG | RDRDY | RIE | DSIE | REN | LL | RTS | DTR | SF/RL |
| 15 | 14 | 13 | 12 | 11 | 10 | 09 | 08 | 07 | 06 | 05 | 04 | 03 | 02 | 01 | 00 |
- DSC - Data Set Change
- IC - Incoming Call
- CTS - Clear to Send
- RR - Receiver Ready; indicates the modem sees a carrier
- RACT - Receive Active; set after the first character has been assembled
- RCVST - Receiver Status Ready
- DMV - Data Move
- SYNFLG - Sync or Flag Detect
- RDRDY - Receive Data Ready
- RIE - Receive Interrupt Enable; allows an input interrupt when Receive Data Ready is set
- DSIE - Data Set Interrupt Enable; allows an input interrupt when Data Set Change is set
- REN - Receiver Enable
- LL - Local Loopback
- RTS - Ready to Send
- DTR - Data Terminal Ready
- SFRL - Select Frequency/Remote Loopback
16xxx2: Receive Data and Status Register (RDSR)
| ERR | ABC | ROR | RA | EOM | SOM | RDAT | |||||||||
| 15 | 14 | 13 | 12 | 11 | 10 | 09 | 08 | 07 | 06 | 05 | 04 | 03 | 02 | 01 | 00 |
- EC - Error Check
- ABC - Assembled Bit Count
- ROR - Receiver Overrun
- RA - Received Abort
- REOM - End of Message
- RSOM - Start of Message
- RDAT - Receive Data Buffer
16xxx2: Parameter Control Sync/Address Register (PCSAR)
| APA | PS | SSLM | SAMS | IMS | EDS | SEC STA/RSYNC | |||||||||
| 15 | 14 | 13 | 12 | 11 | 10 | 09 | 08 | 07 | 06 | 05 | 04 | 03 | 02 | 01 | 00 |
- APA - All Parties Addressed
- PS - Protocol Select
- SSLM - Strip Sync or Loop Mode
- SAMS - Secondary Address Mode Select
- IMS - Idle Mode Select
- EDS - Error Detection Selection
- SEC STA/RSYNC - Secondary Station Address / Sync Character
16xxx4: Parameter Control and Character Length Register (PCSCR)
| TCL | EAF | ECF | RCL | Rsvd | XIE | SQ/TM | XE | MMS | XBE | XA | DR | ||||
| 15 | 14 | 13 | 12 | 11 | 10 | 09 | 08 | 07 | 06 | 05 | 04 | 03 | 02 | 01 | 00 |
- TCL - Transmitter Character Length
- EAF - Extended Address Field
- ECF - Extended Control Field
- RCL - Receiver Character Length
- XIE - Transmit Interrupt Enable
- SQ/TM - Signal Quality / Test Mode
- XE - Transmitter Enabled
- MMS - Maintenance Mode Select
- XBE - Transmitter Buffer Empty
- XA - Transmitter Active
- DR - Device Reset
16xxx6: Transmit Data and Status Register (TDSR)
| XDL | Reserved | XGA | ABORT | EOF | SOM | TDBUF | |||||||||
| 15 | 14 | 13 | 12 | 11 | 10 | 09 | 08 | 07 | 06 | 05 | 04 | 03 | 02 | 01 | 00 |
- XDL - Transmit Data Late
- XGA - Transmit Go Ahead
- ABORT - Transmit Abort
- EOM - End of Message
- SOM - Start of Message
- TDBUF - Transmitter Data Buffer
See also
External links
- DPV11 serial synchronous interface user guide (EK-DPV11-UG-001)
- DPV11 serial synchronous interface technical manual (EK-DPV11-TM-002)
