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Network Working Group J. White Request for Comments: 74 UCSB

                                                      October 16, 1970


 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
 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.

White [Page 1] RFC 74 Network Use of UCSB On-Line System October 16, 1970

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

White [Page 2] RFC 74 Network Use of UCSB On-Line System October 16, 1970

 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 --

White [Page 3] RFC 74 Network Use of UCSB On-Line System October 16, 1970

 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
 |OUT-   |               |  CLASS  |                           |
 |PUT    |       L+8     |   DEP.  |             DATA          |
 |CLASS  |               |  FIELD  |                           |
 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.

White [Page 4] RFC 74 Network Use of UCSB On-Line System October 16, 1970

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

White [Page 5] RFC 74 Network Use of UCSB On-Line System October 16, 1970

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

White [Page 6] RFC 74 Network Use of UCSB On-Line System October 16, 1970

B. Curvilinear Output (Class 2)

 For curvilinear output, the output class field contains the

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
 | X1   | Y1  |  X2  |  Y2  |         ...             | Xn  |  Yn  |
 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
                 Bits 0-3:       unpredictable
                 Bits 4-7:       0011

White [Page 7] RFC 74 Network Use of UCSB On-Line System October 16, 1970

 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

White [Page 8] RFC 74 Network Use of UCSB On-Line System October 16, 1970

 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.

White [Page 9]

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