There are two types of asynchronous serial modules available for Q-bus systems. The first type is the single and multiport serial line unit (SLU) module, which contains discrete serial line units. The second type is the asynchronous serial multiplexer module.
Serial line units are standalone devices that are managed individually and serviced directly by the processor. The processor console must be a serial line unit. These units should be used sparingly in multiuser systems, due to the load they can place on the processor.
Multiplexers contain a number of serial channels, that are managed together as a unit. These modues have large first-in, first-out (FIFO) buffers, and some support DMA transfers. These features reduce the load on the processor. Multiplexers should be used in multiuser systems that need to support lots of terminals, printers, modems and machine-to-machine connections.
The table below contains a comparison of the available SLU modules.
Module Number | M7940 | M8017 | M8028 | M8043 | M8047 | M7195 |
---|---|---|---|---|---|---|
Model Number | DLV11 | DLV11-E | DLV11-F | DLV11-J | MXV11-A | MXV11-B |
Introduced | 1975 | 1977 | 1977 | 1978 | 1980 | 1983 |
Discontinued | 1981 | |||||
Board Size | Dual | Dual | Dual | Dual | Dual | Dual |
Q-bus Address Size | 18-bits | 18-bits | 18-bits | 18-bits | 18-bits | 22-bits |
Serial Ports | 1 | 1 | 1 | 4 | 2 | 2 |
UART Type | AY-5-1013A | AY-5-1013A | AY-5-1013A | 6402 | 6402 | DC319 |
Console Compatible | yes | yes | yes | yes1 | yes2 | yes2 |
Modem Control | no | yes | no | no | no | no |
Current Loop | yes | no | yes | no | no | no |
Maximum Bit Rate | 9600 | 9600 | 9600 | 38400 | 38400 | 38400 |
Split Tx/Rx Clocks | no | yes | yes | no | no | no |
Programmable Bit Rate | no | yes | yes | no | no | yes |
Receiver Active Bit | no | yes | yes | no | no | yes |
Modem Status Bit | yes | no | no | no | no | no |
Maintenance bit | no | yes | yes | no | no | yes |
Error Flags | no | yes | yes | yes | yes | yes |
Boot on Framing Error | no | yes | yes | yes1 | yes2 | yes2 |
AC Bus Load | 2.5 | 1 | 1 | 1 | 2 | 2.3 |
DC Bus Load | 1 | 1 | 1 | 1 | 2 | 0.5 |
+5V Load | 1.0 A | 1.0 A | 1.0 A | 1.0 A | 1.2 A | 3.5 A |
+12V Load | 0.18 A | 0.15 A | 0.15 A | 0.25 A | 0.01 A | 0.06 A |
1
SLU 3 only.
2
SLU 1 only.
The table below contains a comparison of different asynchronous serial multiplexer modules available.
Module Number | M7957 | M3106 | M3104 | M3107 |
---|---|---|---|---|
Model Number | DZV11 | DZQ11-M | DHV11-A | DHQ11-M |
Introduced | 1977 | 1985 | 1984 | 1987 |
Discontinued | ||||
Board Size | Quad | Dual | Quad | Dual |
Q-bus Address Size | 18-bits | 18-bits | 22-bits | 22-bits |
Serial Channels | 4 | 4 | 8 | 8 |
Onboard Processor | no | no | yes | yes |
UART Type | 6402 | DC367B | SC2681 | OCTART |
Modem Control | limited3 | limited3 | yes | yes |
Maximum Bit Rate | 96001 | 96001 | 38400 | 38400 |
Split Tx/Rx Clocks | no | no | yes | no |
Programmable Bit Rate | yes | yes | yes | yes |
Auto Flow Control | no | no | yes | yes |
Maximum Throughput (CPS4) | 10970 | 10970 | 15000 | 60000 |
DMA Support | no | no | yes | yes |
Halt/Reset on Break | no | yes2 | no | no |
AC Bus Load | 1.26 | 1.5 | 2.9 | 3.2 |
DC Bus Load | 1.0 | 1.0 | 1.0 | 0.5 |
+5V Load | 1.15 A | 1.10 A | 4.25 A | 1.90 A |
+12V Load | 0.390 A | 0.236 A | 0.400 A | 0.300 A |
1
Also supports the non-standard bit rate of 19,800 bps.
2
Line 3 only.
3
Can control the DTR output, which can also be jumpered to RTS. Can detect the Ring Indicator and Carrier Detect inputs.
4
Characters per second.
Any of the SLU modules are a good choice. The backplane real estate will likely be one of the primary factors in choosing one of these modules.
Of the multiplexer modules, the M3107 is the top performer, with a fast onboard processor that provides block mode DMA support. It can also overwhelm a system when receiving high volumes of data from connected devices.
The DZ-series of multiplexers are based on the older UNIBUS DZ11 multiplexer, so they tend to have better software support.