General

The X.29 protocol is spoken over an X.25 circuit with an X.3 pad at one end and a program in a "host" at the other end. The X.3 pad communicates with a start-stop ascii terminal. PADP is such a host program and speaks X.29 over the X.25 facilities describesd at (x25).

SIK, SOK and CCK keys are provided that are enough like those designed for Tymnet so as to serve those programs we know of that are designed to use Tymnet style SIK3, SOK3 and CCK3 keys.

PADPF is a factory that accepts an X.25 circuit key and returns SIK, SOK and CCK keys. There should be an X.3 pad at the other end of the X.25 circuit. TCEMK is not provided because few programs use it and the TCEMK functions are not available from X.3 pads.

PADPF also provides the PAD function directly so to let some kind of terminal already connected to the system play the role of a combined X.3 pad and start-stop ASCII terminal.

takes an X25 circuit key CK and returns SIK, SOK and CCK.

Upon expiration of the circuit by signal from the circuit or from either SIK, SOK or CCK, a message is sent via the key FIN thus:

FIN(cause-code,((4,LCN),circuit-info))

cause-code is 0 for clear indication from CK, 1 for kt+1 from SIK, 2 for kt+1 from SOK and 3 for order code 4 on the CCK.

Note that DK(0) serves as FIN if no report is required.

RSEG is a writable segment key to a segment (presumably shared by other PADPF yields) holding an array of 16 byte STATBLOCKs. This PADP will use the STATBLOCK whose index is LCN. 0 <= LCN < 40. The STATBLOCK is formated as