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RFC 411 UNKNOWN MULTICS · TERMINAL

New MULTICS Network Software Features

Case mapping and better allocation handling for Multics network users

On rfc-editor.org ↗
PUBLISHED
November 1972
AUTHORS
M.A. Padlipsky
STREAM
Legacy
CASE MAPPING ACTIVATION
Type MAP on login
EXISTING CONVENTION SOURCE
TENEX Model 33/35 TTY
OVERHEAD REDUCTION
75% of control-message time was for allocations
DOI
10.17487/RFC0411

RFC text

Original text · RFC Editor View on rfc-editor.org ↗ 
Network Working Group                             M. A. Padlipsky
Request for Comments #411                             MIT-MULTICS
NIC 124D3                                       November 14, 1972

                 NEW MULTICS NETWORK SOFTWARE FEATURES

Two recently-installed features of the Multics  Network  software
might be of general interest to the Network community, and should
be of particular interest to those who use Multics via TIP's:

Case Mapping
---- -------

In  order  to allow Network users at upper-case-only terminals on
systems which do not  furnish  case-mapping  to  access  Multics,
typing   "MAP"   (upper-case,   followed   by   Telnet  New-line)
immediately after receipt of the Multics  load  message  actuates
Multics software which applies the following typing conventions:

1) as most Multics  input  is  lower-case,  alphabetic  input  is
    mapped  to  lower-case,  except  for  any  letter immediately
    preceded by "
2) back (left) arrow  is  treated  as  underscore,  up  arrow  as
    circumflex, apostrophe as acute (right) accent
3) escape sequences exist for the following:
    backspace = -
    grave (left) accent = '
    left brace =
    vertical line =
    right brace = )
    tilde = =
4) the sequence "\" is treated as  "
    octal  escape, it is only necessary to type     a "
    them

The case-mapping software is also actuated if "HELP" (upper-case)
is  typed  prior  to  login  in  response  to the system's "login
incorrect" message, in which case the normal  information  (which
would  appear  in response to lower-case "help" as well) on login
format will be printed out.  (Note: the escape sequences are  the
same  as  existing Multics   conventions for direct-dialled Model
33/35 TTY's.  On these particular devices, "
indicated on the key-caps: it is input as SHIFT-L.)

Allocate Handling
-------- --------

Output  to  systems  which give small allocations has long been a
problem, both to the remote user (who experienced frequent pauses
in the output at  his  terminal)  and  to  the  Multics  "Network
Daemon"  process  (which  encountered  considerable  inefficiency
because of being frequently awakened to process the  ALL  control
messages).   To alleviate this, we have introduced interrupt-time
code which processes the ALL's and  outputs  the  next  group  of
bytes  without  causing  the Network Daemon to take a wakeup.  As
attendees of the ICCC will have already observed, response is far
superior under the new scheme.  (System  Programmers  responsible
for  NCP's  might  be  interested  to  know  that some 75% of our
control-message processing deals with ALL's.)


    [ This RFC was put into machine readable form for entry ]
    [ into the online RFC archives by BBN Corp. under the   ]
    [ direction of Alex McKenzie.                      1/97 ]

AI ELI5

On this page
PROBLEMUsers with upper-case-only terminals cannot easily access Multics, which expects lowercase input. Also, sending data to systems with small allocations causes frequent pauses and overhead.
MECHANISMCase mapping translates uppercase to lowercase with special character codes for symbols. Interrupt-time code processes allocation messages without waking the daemon process.
BETTER TERMINAL SUPPORTUpper-case terminal users can work with Multics using special conventions. Network communication with allocation-limited systems becomes faster.

§1Two Improvements for Multics Network Users

Multics network software has added two features to improve usability and performance. The first helps users on upper-case-only terminals access Multics through TIP (Terminal IMP, a network access device). The second speeds up data transfer to systems that offer small buffer allocations.

Two changes make Multics easier to use: one helps special keyboards, and one makes sending files faster.

§2Case Mapping for Limited Terminals

Typing MAP on an upper-case-only terminal activates software that applies typing conventions. Most alphabetic input is mapped to lowercase except after certain characters. Special symbols are typed using escape sequences: Control-H for backspace, and codes for grave accent, left brace, vertical bar, right brace, and tilde. The same conventions are already used for TENEX Model 33/35 TTYs, so they are familiar to some users. Typing HELP before login will also activate case mapping and display login instructions.

These escape sequences match existing Multics conventions for direct-dialed terminals.

When you type MAP, Multics learns your keyboard only has capital letters and translates what you type into the lowercase it expects, using special codes for symbols you cannot type directly.

§3Faster Data Transfer with Small Allocations

Systems that offer small allocations (buffer space for incoming data) used to cause frequent pauses in output and wasted effort in the Multics Network Daemon process, which would wake up repeatedly to handle allocation messages (ALL control messages). The new scheme runs allocation-processing code at interrupt time, handling the messages and sending the next group of data without waking the daemon. Testing shows the improvement is significant. About 75% of network control-message processing time was spent on allocations, so this change substantially reduces overhead.

When sending to computers with small buffers, the old way meant lots of interruptions. The new way handles those automatically so the system does not have to wake up so often.