Chaosnet interface
The Chaosnet UNIBUS interface (also called the CHAOS-11, CH11, QUAD and QAD; there was no generally-used name) and QBCHNI are Chaosnet network interfaces, for the UNIBUS and QBUS respectively. (The two device controllers are identical in programming terms, so they are both covered in this single article.)
They use programmed I/O to transfer data to and from buffers in main memory. They have on-board buffers (one each for inbound and outbound) which can hold one packet of data.
They are both a single quad wire-wrapped card.
Their bus address can be set via DIP switches; the default is 0764140. The network address is also set via a DIP switch.
Device registers
They have 7 registers:
| Register | Abbreviation | Address |
|---|---|---|
| Command and Status Register | CAICSR | 764140 |
| My address (read only) | CAIMYN | 764142 |
| Write buffer (write only) | CAIWBF | 764142 |
| Read buffer | CAIRBF | 764144 |
| Read bit counter | CAIRBC | 764146 |
| Unused | 764150 | |
| Initiate transmission | CAIXMT | 764152 |
| Unused | 764154 | |
| Unused | 764156 | |
| Load interval timer (write only) | CAITIM | 764160 |
In the register contents (below), bits which are read/write or unused are shown in normal font, those which are read-only are in italics, and those which are write-only are shown in bold.
External links
- CHAOS; - includes drawings and documentation
- CHS DEFS - register declarations
- $QUAD LOG - "Log of ChaosNet Interface Boards (quad-high, PDP-11 version)"
- QUAD SETUP - "how to setup .. Chaosnet Interfaces"
- QUAD ECO - "ECO to .. Change cable speed to 4 MHz"
- QADCHS NOTE - random jottings
