The IMP11-A ARPANET interface was a network interface produced by DEC's Computer Special System division for the a UNIBUS, which provided an 1822 interface; the latter could connect to anything that provided a BBN-1822 bit-serial interface, most commonly including IMP interfaces to ARPANET IMPs, but also Packet Radio Network interfaces.
It consists of a BA11-E Mounting Box holding a pair of DR11-B parallel interfaces (the DMA type of DR11 - one for packet input, and one for output), and a custom backplane holding a number of M-series FLIP CHIPs to interface to the IMP, including producing the bit serial input and output. Level converters allow use as either a Local Host or Distant Host interface.
Registers
| Register |
Abbreviation |
Address
|
| Transmit Word Count Register |
TXWCR |
772410
|
| Transmit Bus Address Register |
TXBAR |
772412
|
| Transmit Command/Status Register |
TXCSR |
772414
|
| Transmit Data Buffer Register |
TXDBR |
772416
|
| Receive Word Count Register |
RXWCR |
772430
|
| Receive Bus Address Register |
RXBAR |
772432
|
| Receive Command/Status Register |
RXCSR |
772434
|
| Receive Data Buffer Register |
RXDBR |
772436
|
772410: Transmit Word Count Register (TXWCR)
| WC15 <---> WC00
|
| 15
|
14
|
13
|
12
|
11
|
10
|
09
|
08
|
07
|
06
|
05
|
04
|
03
|
02
|
01
|
00
|
772412: Transmit Bus Address Register (TXBAR)
| BA15 <---> BA00
|
| 15
|
14
|
13
|
12
|
11
|
10
|
09
|
08
|
07
|
06
|
05
|
04
|
03
|
02
|
01
|
00
|
772414: Transmit Command/Status Register (TXCSR)
| ERR |
NEX |
ATTN |
MAINT |
Unused |
CYCLE |
RDY |
IE |
XBA16-17 |
Unused |
LAST BIT |
TX CLR |
GO
|
| 15
|
14
|
13
|
12
|
11
|
10
|
09
|
08
|
07
|
06
|
05
|
04
|
03
|
02
|
01
|
00
|
772416: Transmit Data Buffer Register (TXDBR)
| Data15 <---> Data00
|
| 15
|
14
|
13
|
12
|
11
|
10
|
09
|
08
|
07
|
06
|
05
|
04
|
03
|
02
|
01
|
00
|
772430: Receive Word Count Register (RXWCR)
| WC15 <---> WC00
|
| 15
|
14
|
13
|
12
|
11
|
10
|
09
|
08
|
07
|
06
|
05
|
04
|
03
|
02
|
01
|
00
|
772432: Receive Bus Address Register (RXBAR)
| BA15 <---> BA00
|
| 15
|
14
|
13
|
12
|
11
|
10
|
09
|
08
|
07
|
06
|
05
|
04
|
03
|
02
|
01
|
00
|
772434: Receive Command/Status Register (RXCSR)
| ERR |
NEX |
ATTN |
MAINT |
EOM |
IMP NRDY |
RDY ERR |
CYCLE |
RDY |
IE |
XBA16-17 |
RX ENBL |
HOST RDY |
RX CLR |
GO
|
| 15
|
14
|
13
|
12
|
11
|
10
|
09
|
08
|
07
|
06
|
05
|
04
|
03
|
02
|
01
|
00
|
772436: Receive Data Buffer Register (RXDBR)
| Data15 <---> Data00
|
| 15
|
14
|
13
|
12
|
11
|
10
|
09
|
08
|
07
|
06
|
05
|
04
|
03
|
02
|
01
|
00
|
External links
