1 0 Ref. B6 - NCP : SUPPORT OF INCOMING X29 AND TS29 (Ref. B6) + ___ _______ __ ________ ___ ___ ____ ___ __ 0 Version 2 + _______ _ 0 8 March 1982 + _ _____ ____ 0 P M Girard + _ _ ______ 0 1. For an X29 call, the first byte of the CUDF should contain X'01'. (Values of X'7F' or X'CC' are also acceptable at present if the characters 'XXX' appear in the 6th to 8th bytes of the CUDF). For a TS29 call, the first byte of the CUDF must be X'7F' and the CUDF must contain Transport Service addressing with a "called address" of TS29. 0 2. On DTE no. 1, the service accessed is MAST/ELECTRIC. On DTE no. 2, the service accessed is CP/CMS, emulating an 'ASCII' terminal. 0 3. The following PAD parameters are assumed to be of interest only to the PAD or user, and NCP does not alter them: 1, 2, 5, 6, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18. It reads a few of them at the beginning of the call, but at present makes no use of this information. In the future, NCP may manipulate parameter 2 in connection with password suppression. 0 4. NCP sets the following parameters and assumes that the PAD can comply. The user may of course subsequently alter them, but NCP will not know about this. The parameters set are: 3(=50), 4(=0), 7(=21), 10(=0). As can be seen, NCP sets the output line length parameter to zero, implying transparent output, but leaves the parameters controlling the padding as they are. This should allow NCP to send mixed text and binary at any time, assuming that padding characters are harmless in binary output. 0 5. NCP expects lines of input to be terminated by CR or CRLF. EOT is at present not recognised as a special character, and will be passed to the application as ordinary data. NUL (X'00') is also passed to the application as data. 0 6. As recommended by the SG3 'Green Book' (Ref. A7), X29 output is sent as far as possible as complete packet sequences (M-bit set in full packets when more data follows). When no more data seems to be immediately available from the application, a packet sequence is terminated. 0 7. Although X29 is defined for 128-byte packets and is used over PSS with W=2, P=7, NCP will accept FAST SELECT or non FAST SELECT X29 calls, and the caller may negotiate larger window sizes and 256-byte packets if required. In the absence of negotiation, W=2, P=7 is assumed. - NCP : SUPPORT OF INCOMING X29 AND TS29 PAGE 1 1 0 Ref. B6 - 8. NCP outputs even-parity IA5 (unless instructed by the application to transmit completely transparently). Parity is not checked on input. 0 9. Control-H is always interpreted by NCP as a 'backspace' character, and cannot be input as data. The PAD parameters which control local editing are not altered by NCP, and the user is free to use these as required. 0 10. NCP does not send 'invitation to clear' at the end of an X29 call. Calls to MAST/ELECTRIC are not cleared automatically (unless they time out). Calls to CP/CMS are cleared by NCP a few seconds after the user has disconnected or logged out from the virtual machine. 0 11. For a TS29 call, a Transport Service DISCONNECT message is sent immediately if the user disconnects or logs out from the virtual machine. 0 12. It will be clear from the above descriptions that the implementation conforms only partially at present to the SG3 'Green Book' recommendations. It is regarded as a prototype implementation which will need a further iteration to convert it to its final form. 0 References + __________ 0 A7) Character Terminal Protocols on PSS (PSS User Forum Study Group 3) - - - - - - - - - NCP : SUPPORT OF INCOMING X29 AND TS29 PAGE 2