Silicon Graphics IRIS Workstation User Manual page 154

148 IRIS WORKSTATION GUIDE
K.1 How the IRIS Terminal Program Works
The IRIS terminal program
terminal emulator, and a dispatch routine.
The communication section controls the network connection (where "network" is
taken to mean RS-232, Ethernet (XNS or IP/TCP), or IEEE 488—any reliable
byte-stream protocol). We call the computer on the other end of this network
the remote host, and programs that run there control the IRIS terminal program.
The terminal emulator part behaves like a standard ASCII terminal. Characters
sent to this routine are drawn on the textport, and certain escape characters
have special interpretations (insert line, move cursor, clear textport, etc.).
The dispatch routine reads characters from the network, does the appropriate
thing on the IRIS, and perhaps returns characters to the remote host. When
graphics programs are not being run on the remote host, this usually amounts
to sending every character to the terminal emulator part of the program. If the
IRIS is not in graphics mode, the dispatch routine also sends keystrokes from
the keyboard to the remote host. If the graphical escape character is sent by
the remote host, the dispatch routine will go into graphics mode and will
interpret the next few characters as a graphics command.
The graphical part of the dispatch routine is completely table-driven. The
format of the table below is artificially simple—the exact details appear later in
this document—but we will use it to show how the dispatch routine works.
All of the routines in the IRIS Graphics Library (as well as a few others) appear
in this table. The characters in the parameters column indicate the types of
arguments the commands take. "fff" means that the
floating-point numbers; "ll" means two longs (32-bit integers); "" means that
the command has no parameters; "s" means a short (a 16-bit integer);
clear
"lB" means that the
values are returned as bytes). The last example,
parameters and returns 16 floating-point numbers.
IRIS Terminal Guide
1. See also,
consists of three parts: a communication section, a
1
Token Command
1
move
2
move2i
3
clear
4
color
5
isobj
6
getmatrix
command is sent a long and returns a byte (boolean
isobj
; Appendix F.
Parameters
"fff"
"ll"
""
"s"
"lB"
"F:16"
command takes 3
move
, requires no input
getmatrix
Appendix K:
Version 1.0