Specifications for Network Use of the UCSB On-Line System

Network Working Group                                           J. White
Request for Comments: 74                                            UCSB
                                                        October 16, 1970


       SPECIFICATIONS FOR NETWORK USE OF THE UCSB ON-LINE SYSTEM

Introduction

   UCSB's On-Line System (OLS) is available to Network users as socket
   number x'101' at site 3.  Network users should log in with the
   following OLS accounts parameters:

           USER NUMBER = 196
           ID NUMBER =  57372
           USER NAME = site name -- UCLA, SRI, UTAH, BBN, MIT, SDC, RAND
                       -- whichever is appropriate

   Users communicate with OLS through an intermediary process, hereafter
   called the Interface, which is addressed as socket number x'101'
   (which is termed OLS's "primary socket"), and can be invoked through
   the Logger.  This document is intended to provide programmers with
   the information necessary to communicate with the Interface; and to
   define the input expected and the output returned.  The readers is
   assumed familiar with the Culler-Fried system at UCSB from a user's
   standpoint.  Specifically, this document is not a user's manual for
   OLS.

   The interface conducts all Network transactions through the NCP,
   which operates under the Host-Host protocol of 3 August 70.  The
   first message sent by the Interface is of Type 0: the first eight
   bits are zeros and thereafter, for the life of the connection Imp-
   message boundaries are not significant.  Similarly, the Interface
   expects the first message it receives to be Type 0, discards the
   first eight bits assuming them to be zeros, and thereafter for the
   life of the connection takes no notice of Imp-message boundaries.

   A word about terminology.  The 360/75 is a 32-bit machine, but its
   instruction set is byte-oriented.  A byte is eight bits, and those
   eight bits are numbered 0-7 from left to right.  Terms such as

   "listen", "request connection", "accept a connection", and "reject a
   connection" are used freely herein to describe those primitive
   Network functions, which are user at a foreign site presumably has
   available to him through his NCP.  They are used here in the same
   senses in which they have frequently been used in the NWG literature.

Logging Into the Interface

   To use the On-Line system, the Network user must establish a full-
   duplex connection with the Interface.  The Interface is core resident
   only while at least one such duplex connection is established (i.e.,
   while at least one Network user is connected).  At all other times,
   the Interface resides on direct-access storage and must be invoked
   through the Logger.  A login sequence can always be initiated by
   requesting connection to OLS's primary socket.  While in core, the
   interface listens on that socket and will accept any call it
   receives; at all other times, the _Logger_ listens on that socket and
   will _reject_ the first call it receives, read the Interface into
   core, and dispatch it.  The Interface will then listen on the primary
   socket as before.  Thus, to initiate a login sequence, the user
   requests connection to the primary socket.  If accepted, he is in
   contact with the Interface.  If rejected, he should reissue the
   connection request; when accepted, he will be connected to the
   Interface.  A second rejection would indicate that the On-Line System
   was inactive, or that either the Interface or the NCP had exhausted
   its resources.

   Over this initial connection, the Interface will send eight bits of
   zeros, indicating message type zero, followed by a 32-bit socket
   number, which it will select from a pool of socket numbers allocated
   to it.  It will then promptly close the connection and reissue the
   listen, to allow other users to begin login.  It will then request
   connection of the local socket whose number was sent to the user,
   with the foreign socket whose number is one greater than that of the
   user's socket.  Similarly, it will request connection of the local
   socket whose number is one greater than that sent to other user, with
   the user's socket.  Once the two connections have been established,
   the Interface will consider the user logged in.

   The two connections thus established are maintained indefinitely by
   the Interface.  Over its receive connection (hereafter termed the
   "Input Connection"), the Interface accepts input fro OLS.  Over its
   send connection (the "Output Connection"), the Interface relays
   displays from OLS generated in response to the input.  The Interface
   will terminate the connections only should the On-Line System
   terminate.  The user is expected to close the two connections when
   finished, making the local sockets available for reallocation, at
   which time the Interface will consider the user logged off.

The Input Connection

   With the exception of the first tow bytes, data received by the
   Interface over the Input connection is treated as a continuous stream
   of one-byte key codes, potentially endless in extent.  The Interface
   passes each key code -- unexamined -- to the On-Line System, which in
   turn processes it exactly as it would input from a keyboard connected
   directly to the System.  The set of valid key codes and its relation
   to the standard OLS keyboard are depicted in Figure 1.  The Interface
   makes no validity check of the incoming data, but OLS will detect and
   discard invalid key codes.

   Normally, the first keys sent over the input Connection (i.e., the
   first keys that the Network user pushes) should be those necessary to
   log in to OLS.  The user may log in and out many times during the
   life of the Network connection, and these operations are transparent
   to the Interface.  The last key s sent over the Input Connection
   should log the user off of OLS (_SYST DOWN_).  Failing to log off
   before terminating the Network connection allows the possibility of a
   later Network user's finding himself already logged in.

   The first byte of data received over the Input Connection is
   discarded unexamined by the Interface, which assumes it to be zeros
   indicating message type zero in compliance with Host-Host protocol.
   No significance is attached to Imp-message boundaries.  The second
   byte of data received is not passed to OLS but is examined by the
   Interface.  By appropriately selecting that second byte, the user can
   cause to be suppressed by the Interface, any or all of the three
   classes of output generated by OLS and potentially relayable to the
   user over the Output Connection.  The byte is interpreted as follows:

           Bit     0  =    1: suppress all alphanumeric output.
           Bit     1  =    1: suppress all curvilinear output.
           Bit     2  =    1: suppress all special character output.
           Bits    3-7:       not examined, should be zeros.

   Once made, this declaration prevails for the life of the Network
   connections.  A user can avoid transmission of output classes he is
   unable to process and would therefore have to discard anyway, thus
   avoiding needless network traffic.  A user operating from a teletype
   and capable of displaying only alphameric output, for example, might
   specify x'60' and thereby suppress all else.

   Figure 1. Input Key Code Set [Please view PDF version.]

The Output Connection

   With the exception of the first byte, data transmitted over the
   Output Connection by the Interface consists of a continuous string of
   variable-length records.  The first byte sent consists of zeros,
   indicating message type zero, to comply with Host-Host protocol, and
   should be discarded by the user.  At present there are three classes
   of records defined, one corresponding to each class of OLS output --
   alphameric, curvilinear, and special characters.  Only records of
   those classes, which have been enabled by the user will be
   transmitted; all other output will be suppressed locally by the
   Interface.  Each record consists of a one-byte field specifying the
   output class, a one-byte output-class-dependent field, a variable-
   length data field, and a two-byte field containing the combined
   length in bits (unsigned) of the data and output-class-dependent
   fields.  Each record has the following form:

      1            2            1                 L        bits
   ---------------------------------------------------S-----------
   |OUT-   |               |  CLASS  |                           |
   |PUT    |       L+8     |   DEP.  |             DATA          |
   |CLASS  |               |  FIELD  |                           |
   ---------------------------------------------------S-----------

   The integer above each field is the length of that field in bytes
   (except where stated to the contrary).  The lengthy of a cord, then
   is given in bits by the contents of the length field plus twenty-
   four.  The significance of the data and class-dependent fields, and
   the output class assignments are given in the following sections for
   each output class.

A.  Alphameric Output (Class 1)

   For alphameric output, the output class field contains the following:

           Bits 0-3:       unpredictable
           Bits 4-7:       0001

   The contents of the class-dependent field are unpredictable.  The
   data field contains the alphameric display in the form of a
   contiguous string of one-byte characters.  Any character listed in
   Figure 2 may be present.  The list includes the Greek and Latin
   alphabets, a variety of special symbols, as well as carriage control
   characters such as carriage return, line feed, backspace, and erase.

   Alphameric output records embody system-generated messages, LIST mode
   displays, lower keyboard activity on the TYPE level, TYPE level
   operators such as UP and DOWN, etc.  The appearance of the character
   pair 'BACK ERASE' (x'59BC') in a record represents a command to erase
   the display scope.  When not immediately followed by ERASE, BACK
   indicates a backspace operation.  'BREAK' (x'79') is used to
   facilitate formatting of long messages that may be either printer- or
   display-scope- destined.  In generating scope display, where there
   are twenty-five characters per line, 'BREAK' should be interpreted as
   a carriage return; in generating printer output, where longer lines
   are possible, it should be interpreted as a space or blank.

Figure 2. Alphameric Output Character Set

   NAME  Lower     CODE            NAME            Upper           CODE
         Case                                      Case

   A               C1              ALPHA                           81
   B               C2              BETA                            82
   C               C3              CHI                             83
   D               C4              DELTA                           84
   E               C5              EPSILON                         85
   F               C6              PI                              86
   G               C7              GAMMA                           87
   H               C8              THETA                           88
   I               C9              IOTA                            89
   J               D1              SIGMA                           91
   K               D2              KAPPA                           92
   L               D3              LAMBDA                          93
   M               D4              MU                              94
   N               D5              ETA                             95
   O               D6              OMICRON                         96
   P               D7              PI                              97
   Q               D8              PHI                             98
   R               D9              RHO                             99
   S               E2              SIGMA                           A2
   T               E3              TAU                             A3
   U               E4              UPSLION                         A4
   V               E5              NU                              A5
   W               E6              OMEGA                           A6
   X               E7              XI                              A7
   Y               E8              PSI                             A8
   Z               E9              ZETA                            A9
   0               F0              ss 0                            B0
   1               F1              ss 1                            B1
   2               F2              ss 2                            B2
   3               F3              ss 3                            B3
   4               F4              ss 4                            B4
   5               F5              ss 5                            B5
   6               F6              ss 6                            B6
   7               F7              ss 7                            B7
   8               F8              ss 8                            B8
   9               F9              ss 9                            B9
   NAME            CODE            NAME                    CODE

   PLUS +          4E              UNDERSCORE _            6D
   MINUS -         60              AT SIGN @               7C
   SLASH /         61              POUND SIGN #            7B
   APOSTROPHE '    7D              CENT SIGN [cent sign]   4A
   LOGICAL AND &   50              DOLLAR SIGN $           5B
   ASTERISK *      5C              PERCENT SIGN %          6C
   EQUALS =        7E              COLON :                 7A
   SEIM-COLON ;    5E              LEFT BRACKET [          73
   LEFT PAREN (    4D              RIGHT BRACKET ]         74
   RIGHT PAREN )   5D              LESS THAN <             4C
   COMMA ,         6B              GREATER THAN >          6E
   PERIOD .        4B              QUOTE "                 7F
   QUESTION MARK ? 6F              LOGICAL NOT [half arrow] 5F
   LOGICAL OR |    4F              EXCLAMATION !           5A


           Carriage                        Special List
           Control                         Mode Characters

   BACK (backspace)        59      SPACE  _                    62
   RETURN (carriage        49      POST LIST :                 63
           return)                 DIVIDE [0with /]            64
   TAB (advance to next    77      MULTIPLY [0 with .]         65
           line)                   SUBTRACT [0 with -]         66
   UP (line feed up)       06      ADD [0 with +)              67
   ENL (line feed up)      27      CARRIAGE RETURN
   DOWN (line feed down)   07      [diagonal left down arrow]  68
                                   DELETE [box with ///]       69
   CON (line feed down)    28      Pointer _                   6A
   RS (position to         13
           upper left of                   Miscellaneous
           display area)
   ERASE                   BC
   BREAK (for display      79
           scope: RETURN           DOT (curvilinear            78
           for line                    display
           printer: SPACE)             dot-dot mode)
   SPACE (blank)          40

   Note:
   Codes are specified in hexadecimal and are eight bits.  'ss' means
   'superscript'

B.  Curvilinear Output (Class 2)

   For curvilinear output, the output class field contains the
   following:

Bits 0-1:             00      indicates line segment mode (adjacent
                              display points are to be connected by
                              straight lines)
                      01      indicates dot mode
                      10      indicates character mode (the
                              class-dependent field contains a
                              character from Figure 2 which is to be
                              displayed at each point ('dot-dot' mode is
                              character mode with the display
                              character 'DOT' (x'78')).
Bits 2-3:                     unpredictable
Bits 4-7:                     0010

   For character mode, the class-dependent field contains the display
   character; in other cases, the contents of that field are
   unpredictable.  The data field contains a list of X-Y display
   coordinates as depicted below:

     2     2       2       2                               2      2
   --------------------------------------S----------------------------
   | X1   | Y1  |  X2  |  Y2  |         ...             | Xn  |  Yn  |
   --------------------------------------S----------------------------

   Xi and Yi are the X and Y display coordinates -- after scaling -- of
   the ith component of the vector represented by this record.  Each
   coordinate is contained in a two-byte field, therefore one component
   in four bytes, and hence the context of the vector being displayed is
   given by the contents of the length field minus eight divided by
   thirty-two.  The assumed display area is square, with original at
   lower left, and both X and Y ranging between 0 and 4095.  There is a
   one-to-one correspondence between vectors displayed and curvilinear
   output records transmitted.

C. Special Character Output (Class 3)

   For special character output, the output class field contains the
   following:

                   Bits 0-3:       unpredictable
                   Bits 4-7:       0011

   The contents of the class-dependent field are unpredictable.  The
   data field contains a contiguous string of variable-length
   characters, each representing either a move in one of sixteen
   directions or a change in position relative to the lower right corner
   of the last character frame (where for alphameric) and special
   character display, the display area is square, 4096 units in extent
   vertically and horizontally, and a character frame is 160 units wide
   and 224 units high).

   The sixteen characters, which define move operations are listed in
   Figure 3, and each is one byte long.  Such a character indicates a
   move from the current position, in the specified direction, a
   distance equal to that of a move in the same direction from the
   center of a 64-unit square to its perimeter.  The length of the move
   is therefore functionally related to its direction.

   A change in position relative to the lower right corner of the last
   character frame is represented by a four-byte character of the form:

   1               12 bits         12 bits
   -----------------------------------------------
   | x'70' |     [delta] X        |   [delta] Y  |
   -----------------------------------------------

   where [delta] X and [delta] Y are signed quantities indicating the
   number of units change along each coordinate.

Figure 3. Special Character Vector Character Set

   Direction                       Code
   000.0                           47
   022.5                           48
   045.0                           51
   067.5                           52
   090.0                           53
   112.5                           54
   135.0                           55
   157.5                           56
   180.0                           57
   202.5                           58
   225.0                           41
   247.5                           42
   270.0                           43
   292.5                           44
   315.0                           45
   337.5                           46
   Note:
   Codes are specified in hexadecimal and are eight bits.

   Directions are specified in degrees, increasing counter-clockwise
   from 0o at positive X in an X-Y coordinate system.


   * Text enclosed in brackets describe non-ascii characters that were
     present in the original document.  Please see the PDF file for the
     actual representations.