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Network on-line operators (RFC0121) Disclosure Number: IPCOM000004869D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2019-Feb-10
Document File: 13 page(s) / 16K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

M. Krilanovich: AUTHOR

Related Documents

10.17487/RFC0121: DOI

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 12% of the total text.

Network Working Group M. Krilanovich Request for Comments: 121 Computer Research Lab, UCSB NIC: 5833 21 April 1971



The operators described in this document have been implemented within UCSB’s On-Line System and make the Network (via the NCP) accessible to On-Line System users.

A set of operators is provided to facilitate the use of the Network by On-Line System users. The operators are defined on LVL I on system ’NET’, and serve an an interface between the users and the Network Control Program (NCP), which supervises all Network operations at this site.

A concept fundamental to On-Line System Network operations is that of a completion code variable. Associated with each socket that is not in the closed state is a unique variable, called a completion code variable. This variable serves two purpose: it identifies the local socket referenced, and upon completion of the operation it contains a completion code to indicate the outcome of the operation to the user. It may be used at any time for any purpose other than Network operations. Its value at the beginning of a Network operation is immaterial rather it is the variable itself that is important. In all Network operations, whenever a completion code variable is called for, the only acceptable type variable is a LO storage location, either case 1 or case 2.

In those operations requiring a socket to be specified by its socket identifier, the following format is used: the site number of UCSB is always used for local sockets, and so this item is never specified. The site number of a foreign socket, if specified, must be a positive integer or a LO storage location, and must be less then 256 in value. If not specified, the site number of a foreign socket will default to the site number of UCSB. A socket number is specified as an integer, either unsigned, in which case it is assumed to be positive, or with an explicit minus sign, or a LO storage location, of any value. Negative socket numbers are represented internally in two’s complement form and therefore for the purpose of the gender of a socket, a socket number is even or odd according to whether its absolute value is even or odd, respectively.

Krilanovich [Page 1]

RFC 121 Network On-Line Operators April 1971

In all operations involving the On-Line System Network operators, there are certain conventions concerning the format of the data sent and received. The data is grouped in ’messages’ consisting of three fields, op code, length, an text, in that order. The op code is one byte in length and is a code which indicates how the text field is to be interpreted. The length field is two bytes long, and gives the length, in bits, of the text field, which contains the actual data. (The op code and length fields together are termed a header.)

The following op codes are presently defined:

op code meaning

0 This op code is a NOP. No text field exists, and the contents of the length field are unpredictable. (This op code is...