💾 Archived View for gemini.bortzmeyer.org › rfc-mirror › rfc74.txt captured on 2023-07-22 at 22:21:43.
⬅️ Previous capture (2021-11-30)
-=-=-=-=-=-=-
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.
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
---------------------------------------------------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.
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
Note:
Codes are specified in hexadecimal and are eight bits. 'ss' means
'superscript'
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
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
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
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.
White [Page 9]