As per Relevance of the word terminal, we have this rfc below:
Network Working Group NIC 5739
Request for Comments: 96 Richard W.
Category: Informational SRI-
12 February 1971
An Interactive Network Experiment to Study Modes of Access the
Information
1.
This NWG/RFC outlines the framework for a simple
experiment to study modes of access to the Network Information
(NIC). A detailed specification for the initial access conventions
the NIC is contained in NWG/RFC 97, NIC (5740,). The initial
service to be provided by the Network Information Center are
around the SRI-ARC (ARC) Online System, typewriter version - NLS(T).
These services will involve creation, manipulation, searching,
distribution of symbolic material (text initially). The initial
System was display oriented and considerable development has gone
the study of features required for a comfortable interface to the user
In preparation for use with the Network Information Center, a
oriented version has been developed. Assuming good computer response
a typewriter terminal operating at 30 char/sec, the system
powerful and comfortable to use capabilities for handling
textual material
The question to which the experiment, to be described below
addresses itself is to determine how to extend these
through the network to users at remote sites, possibly operating 10
char/sec and higher speed terminals through fairly heavily
systems. This experiment will also provide useful information about
interactive characteristics of the network, and guidelines for
of other interactive systems to be used with the network. We
that this experiment will be conducted with the assistance
cooperation of one other site. We estimate that the experiment
require about three calendar months. In order to minimize the
required for the experiment, we will collect meaningful response
statistics that are easy to obtain with presetly existing
facilities in the SRI and cooperating site systems, and
performance measuring facilities. We will not conduct
productivity studies with the users of the connection, but will
their subjective impressions on use of the various connection modes.
result will be data indicating the costs and benefits obtained using
types of access described below. We would expect that this
would be useful to sites in determining how they want to
access to the NIC and other interactive sites
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NETWORK WORKING GROUP RFC #96 NIC 5739
During the period of the experiment, other sites will want to access
NIC as they come up on the network. We would recommend a
approach, such as described in Section 2b, initially with a
change later if the experiment indicates improved response and/or
factors coupling can be obtained with one of the other approaches
NWG/RFC 97, NIC (5740,) specifies this initial access approach
detail
2. Getting Connected to the
2a.
There are three basic approaches to allowing remote sites
connect to the NIC through the network, which we can call
Program Telnet, NLS(T) Front End, Monitor Telnet. Each of these
discussed below. Each approach requires code which will run in
remote host
We assume that standard conventions for Telnet programs will
specified by the Network Working Group. In the companion
(NWG/RFC 97), NIC (5740,)) we include recommended conventions
solving those problems which we are aware exists relative to
NIC access, although we have tried to specify conventions useful
generally. The NLS(T) Front End Program would interface to the
Program
We assume that no matter which approach is taken, the
at the ARC end use the information obtained during the
process to log-in the remote terminal under a general account
will place the terminal user in the NIC version of NLS, which we
call NLS(NIC) for short. The NLS(NIC) will ask the terminal user
his initials. The remote user then has access to all NIC facilities
The initial typewriter oriented system accepts commands of
general form
...
The is usually two words, the first to
a general operation class, and the second to indicate a general
structure type to be operated on. The s specify
data entities to be operated upon, or instructions to adjust
parameters
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NETWORK WORKING GROUP RFC #96 NIC 5739
The system at ARC is full duplex and allows the user to type
first character of the command words and the system immediately
the remaining characters as feedback and support for the user.
feedback is echoed where appropriate. The question we need to
is what changes in this system will be required to suit it to
network and remote site constraints. We now look at problems
at the remote sites
To gain connection to the NIC we assume that the user logs
his local system and calls up a subsystem or cusp. This subsystem
system program, Telnet program will be used to access other sites
well. The remote terminal and its controlling software system
operate in three basic modes as seen by the host
Case 1 - Character at a time half
Case 2 - Character at a time full
Case 3 - Line at a time half
Although line at a time is full duplex is a logical possibility
no such approach is in general use and we ignore it in the
discussion
In the discussions to follow, in Section 2b, 2c and 2d, we
the modes of access which we would like to
experimentally. We want to study user reaction with 10 char/sec, 15
char/sec, and 30 char/sec devices
2b. User Program
Consider the above classes of terminal in turn and the ways
Telnet program might handle communications between them and the NIC
The Telnet program might allow both full and half
communication as specified by the user
2b1. Case 1 - Character at a Time Full
The simplest approach would be for the Telnet program
take each character received from the terminal (except a
character or character sequence needed to escape back to
terminals host system), convert the code to ASCII and transmit
as a message to NLS(NIC). NLS(NIC) would handle all
echoing and transmit echo messages back to the Telnet for
transmission to the terminal in the appropriate terminal code
This mode of communication involves full duplex transmission
to user and is probably the severest test of the
characteristics of the host-network-host system
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NETWORK WORKING GROUP RFC #96 NIC 5739
Depending on loading at the remote host, on the network,
at ARC, round trip delay for simple character echoing may
several seconds. Experience in communication between the old
940 and a heavily loaded PDP-10 at Utah showed occasional
on the order of 4 or 5 seconds and longer for single
echoing. Human factors considerations in use of NLS(NIC)
that such delays would be frustrating to the user. A more
study of this mode of communication should give a base
which to measure the other modes of communication
2b2. Case 2 - Character at a Time Half
There are two subcases which we treat identically
i) The Telnet program sees a half duplex terminal
ii) The Telnet program sees a full duplex terminal,
provides echoing so as to make the terminal half duplex as
by NIC
With the character at a time half duplex case the NIC
will operate in two modes
a) short
b) long
In short mode the user will type in the command and receive
his terminal only the characters echoed by his system and
NIC response to the command
In long mode. the user will receive feedback from NIC at
appropriate point in the command. We want to see how novice
experienced users feel about working in these two modes,
the delays in the system response
2b3. Case 3 - Line at a Time Half
From the point of ciew of the NIC this case is essentially
same as Case 2. From the point of ciew of the network
case is a more efficient use fo the network as the messages
longer. This case is also more efficient for the user
system as it will require fewer calls to the Telnet subsystem
response for Case 3 may be better than Case 2.
[Page 4]
NETWORK WORKING GROUP RFC #96 NIC 5739
2c. The NLS(T) Front
In this mode of communication, the subsystem which
communication with the NIC is to perform some of the
and other tasks now performed by NLS(T). The type of tasks to
performed are echoing of the characters typed and the
feedback characters for the full spell out of the command words
parsing of the command string, error handling where appropriate
and the sending of a parsed string as a message to NLS(T). If
should turn out that this mode of communication is the
preferred by sites, we would expect to supply an example
of the Front End program written in some language to serve as
model for implementation. The Network Working Group may want
give further study to a standard language for specifying
programs as indicated in NWG/RFC 51, NIC (4752,).
2d. Monitor
Much of the response delay in the experiments of Section 2
is expected to result from the fact that the Telnet
there is a user program. We will run the experiments of Section 2
with the appropriate Telnet routines resident as a part of
user host monitor
[ This RFC was put into machine readable form for entry ]
[ into the online RFC archives by Henrik Johansson 4/97 ]
[Page 5]
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