Tymshare Base-Host Protocol
From Computer History Wiki
This documents the protocol, as used around 1975, between a PDP-10 host and Varian 620 Tymbase.
Packets start with a 4-octet header. More data may optionally follow after the header, depending on the packet type.
Packet type | Port | Subtype | Data |
Packet types. Any number not in this list is illegal.
Number | Name | Comment |
1 | ANS | System is answering. |
2 | SHT | System is up but shut. |
3 | CRS | Sender is crashed. |
4 | DIE | Recipient should crash. |
5 | NSP | Base taken over by new supervisor. |
6 | LOG | Login, next 4 data characters are the info about terminal type, and port or origin, then name, etc. |
7 | AUX | Supervisor response to establishing auxillary circuit. |
10 | NOP | Backpressure on. |
11 | OUP | Backpressure off. |
12 | GOB | Character gobbler. |
13 | ZAP | Circuit zapper. |
14 | EDC | Enter deferred echo mode. |
15 | LDC | Leave deferred echo mode. |
16 | GRN | Green ball. |
17 | RED | Red ball. |
20 | YEL | Yellow ball. |
21 | ORG | Orange ball. |
22 | HNG | Hang character - not used. |
23 | ETM | Enter 2741 transparent mode. |
24 | LTM | Leave 2741 transparent mode. |
25 | LOS | Lost ball, data has been lost from buffers. The data filed may tell how many were lost. |
26 | SUP | Supervisor request (aux circuits). |
27 | SUR | Supervisor response (aux circuits). |
30 | AXC | Supervisor string character. |
31 | TSP | Test pattern probe. |
32 | TSR | Test pattern response. |
33 | SAD | Host sad. |
34 | ECN | Echo on. |
35 | ECF | Echo off. |
36 | TCS | Term characteristics, first data byte indicates which characteristics second data byte indicates value to set to. |
37 | TCP | Term characteristcs probe, data byte indicates which terminal characteristic were requested. |
40 | TCR | Term characteristcs response, data is just like TCS, comes in response to a probe; also is reflected by remote when terminal characteristics are sent. |
41 | HSI | Host up and answereing with # of ports in port byte, and host # in data byte. |
This information comes from the SUMEX-AIM monitor file TYMSRV.MAC, written by Michael A. Heathman in 1975.