Telnet extended ASCII option (RFC0698)
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2019-Feb-14
Internet Society Requests For Comment (RFCs)
Describes an option to allow transmission of a special kind of extended ASCII used at the Stanford AI and MIT AI Labs.
Request for Comments: 698 Jul 1975 NIC #32964
TELNET EXTENDED ASCII OPTION
1. Command Name and Code.
2. Command Meanings.
IAC WILL EXTEND-ASCII
The sender of this command requests Permission to begin transmitting, or confirms that it may now begin transmitting extended ASCII, where additional ’control’ bits are added to normal ASCII, which are treated sPecially by certain programs on the host computer.
IAC WON’T EXTEND-ASCII
If the connection is already being operated in extended ASCII mode, the sender of this command demands that the receiver begin transmitting data characters in standard NVT ASCII. If the connection is not already being operated in extended ASCII mode, The sender of this command refuses to begin transmitting extended ASCII.
IAC DO EXTEND-ASCII
The sender of this command requests that the receiver begin transmitting,or confirms that the receiver of this command is allowed to begin transmitting extended ASCII.
IAC DON’T EXTEND-ASCII
The sender of this command demands that the receiver of this command stop or not start transmitting data in extended ASCII mode.
IAC SB EXTASC
<high order bits (bits 15-8)><low order bits (bits 7-0)> IAC SE
This command transmits an extended ASCII character in the form of two 8-bit bytes. Each 8-bit byte contains 8 data bits.
TELNET EXTENDED ASCII OPTION RFC 698, NIC 32964 (July 23 1975)
i.e., only use standard NVT ASCII
Several sites on the net, for example, SU-AI and MIT-AI, use keyboards which use almost all 128 characters as printable characters, and use one or more additional bits as "control’ bits as command modifiers or to separate textual input from command input to programs. Without these additional bits, several characters cannot be entered as text because they are used for control purposes, such as the greek letter "beta’ which on a TELNET connection is CONTROL-C and is used for stopping ones job. In addition there are several commonly used programs at these sites which require these additional bits to be run effectively. Hence it is necessary to provide some means of sending characters larger than 8 bits wide.
5. Description of the option.
This option is to allow the transmission of extended ASCII.
Experience has shown that most of the time, 7-bit ASCII is typed, with an occasional "control’ character used. Hence, it is expected normal NVT ASCII would be used for 7-bit ASCII and that extended-ASCII be sent as an escape character sequence.
The exact meaning of these additional bits depends on the user program. At S...