BMUG PD-ROM 1995 Fall/PD-ROM F95.toast/Telecom/Terminal Programs/Terminal 2.0.1 ƒ/Terminal.doc

Text File | 1990-12-19 | 31.9 KB | 733 lines | [TEXT/ttxt]

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"Terminal"                 A Serial Communication Program For The Macintosh
===========================================================================

                        Version 2.0 (20-Nov-1990)


___________________________________________________________________________
INTRODUCTION


"Terminal" is a serial communication program for the Macintosh computer.
Features are:

* Fast display. No characters are lost for up to 4800 Baud on a Mac Plus,
or up to 9600 Baud on a Mac IIcx in 1-bit color mode, with text capture to
disk enabled. (For most commercial programs this only holds for short term
until the serial input buffer is full.)

* Capture buffer, so that the last 32768 (default, can be configured, upper
limit is 32768 lines) characters are always available in the scrolling
terminal window. The buffer can be saved as TEXT file to disk or appended
to an existing file. Very fast scrolling to move around in the buffer.

* Text capture to disk, so that everything received or transmitted is saved
automatically to a TEXT file on disk. Can also be appended to an existing
file.

* Send TEXT files from disk, from up to 10 different macro buffers or from
the clipboard. Wait for prompt string before sending line, delay after each
line, delay after each character.

* XON/XOFF, CTS, DTR and CTS/DTR handshake. Hardware handshake is useful
for high speed modems or terminal node controllers.

* Binary file transfer using X-Modem protocol (checksum, CRC or 1K
options), Y-Modem (i.e. XModem batch), Z-Modem or CompuServe QuickB
protocol (up- and download). Automatic recognition of MacBinary (I and II)
file format.

* Built-in C interpreter with a rich set of intrinsic functions to execute
scripts from TEXT files. Scripts can be as simple as modem setup, dial or
auto-logon, but can also be used to program a complete BBS.

* Very compact program. Only about 90K on disk and can run in a 160K
partition under MultiFinder.

* Complete non-modal user driven program (even during file transfers). Runs
in the background under MultiFinder (even if "Set Aside" under
MultiFinder). Several copies of the program may be run at the same time,
under MultiFinder, each one on a different serial port.

* Recognizes and uses all serial devices that are correctly registered with
the Communications Toolbox.

* The program is free.

* Source code is free (can be compiled with THINK C 4.02 or MPW 3.2 C).


___________________________________________________________________________
CONFIGURATION


"Terminal" was developed (in THINK C 4.02 and MPW 3.2) and tested on a
Macintosh Plus and on a Macintosh IIcx with System 6.05 under MultiFinder
6.1b9 (The MultiFinder with the "Set Aside" option). The program is
MultiFinder aware and can work in the background even if "Set Aside". HFS
(hierarchical file system) and 128K ROMs (or newer) are required, so
"Terminal" will not run on "old" Macs and needs at least a Mac Plus.
"Terminal" was tested and runs fine with System 7.0b1 (October release).

I made no special attempts to stay compatible with old system versions, nor
was the program tested on old system versions. But I made every effort to
follow Apple's rules in order to stay compatible with future systems and
hardware. (The only exception is the script function getdcd() where I had
to read the status register of the SCC directly.)

"Terminal" will recognize all serial devices that are correctly registered
with the Communications Toolbox, but otherwise does not use or require the
Communications Toolbox.


___________________________________________________________________________
FILES AND FOLDERS


* "Terminal" the application, can be anywhere on your disk.

* "Terminal Folder" is a folder that should be created in the same folder
as the "Terminal" application. All scripts (a script is a TEXT file with a
suffix of ".s") in this folder will be included in the "Scripts" menu for
easy execution. If this folder does not exist, all scripts in the same
folder as the "Terminal" application will be included in the "Scripts"
menu. This script folder, or the application folder if the script folder
does not exist, is also used as the default folder for loading macro files
by the script language (function "macrol"). If there is a file named
"Macros.m" in this folder it will be loaded as the macro set at startup.

* "Terminal Settings" is created by "Terminal" in the "Terminal Folder", or
in the application folder if "Terminal Folder" does not exist, to store the
options selected. If this file is not found when "Terminal" starts up,
default options will be used. In this file are also stored the current
positions of the terminal and the progress window, so that they will be
positioned again at the same location when the application is restarted.
(The settings file is not stored in the System folder so that multiple
copies of "Terminal" can run on the same machine, under MultiFinder, each
one on a different port.)

* The "Terminal options" menu can be used to select a start-up script, that
will be automatically executed when the application is started. This script
can be anywhere on the disk. By default there is no start-up script. A
script can force "Terminal" to quit when the script has finished. Using
this feature and a startup script you can use Terminal to make file
transfers from inside HyperCard stacks (you can even make HyperCard modify
the startup script before running Terminal), or from other programmable
applications that support launching other applications.

* Scripts can be started from the Finder by double-clicking (opening) if
their creator was changed from the creator of the TEXT editor that created
them to Terminal's creator. See the "Kiss script file" command in the
"File" menu description.

* For use with Y-Modem batch, Z-Modem and CompuServe QuickB file transfers
a folder must exist on the disk where all downloads and uploads using these
protocols will look for and store files. This folder can be selected by
using the "File transfer options" menu option. The default folder is the
same as the folder containing the "Terminal" application. This folder is
also the default folder used by script file commands.


Note: If you had a previous version of "Terminal" on your disk please
rebuild the Desktop file (hold down the option and the command key when
booting) so that the Finder recognizes the new icons and file types.


___________________________________________________________________________
THE TERMINAL WINDOW


There is a fixed size window with 24 lines and 81 columns (default values,
can be configured). The window can be moved anywhere on the screen. A
vertical scroll bar allows fast moving around in the last 32768 (default
value, can be configured) characters received. If a new character is
received the text automatically scrolls to the end. Everything received is
displayed in the terminal window, even if the window is not the frontmost
or if the application was switched out under MultiFinder.

Note: "Terminal" tries to scroll the window as fast as possible. If the
window is partially covered by other windows, the scrolling slows down some
what. If during scrolling you move windows around, the terminal window
might not update correctly. In this case simply click inside the terminal
window to force "Terminal" to redraw the whole window.

The name of the window will be "Terminal" if no script is executing,
otherwise the window name will be the same as the name of the script file.
To cancel a running script select it again under the corresponding menu
item.

If the terminal window is frontmost everything typed on the keyboard is
transmitted. If the local-echo option is selected it is also echoed to the
window. To send control characters the "Option" key (in this case all
characters that are only available by using the "Option" key are no longer
available) or the "Command" key (in this case the "Command" key cannot be
used to select menu commands) can replace the "Control" key, if your
keyboard doesn't have one.

After file transfers a statistics message is displayed in the top area of
the window showing how much bytes were transferred in how much time. This
area is also used to display error messages. If a message is displayed a
button appears to the left of it. Clicking this button will erase the
message and the button. Note that such a message is not a modal dialog but
will stay as long as there is no new message or until it is cleared.
Meanwhile the program continues its normal operation.

During file transfers a progress window (this is a non-modal window, not a
modal dialog box, and can be moved around or deselected, and all menu
commands are still available while this window is up) is displayed. This
progress window shows the progress of the file transfer and has a "Cancel"
button. By clicking in this "Cancel" button the file transfer can be
aborted. The file transfer can also be canceled by selecting the
corresponding menu item. If the progress window gets lost beneath other
windows, use the "Edit" menu item "Show progress window".

Characters received in terminal mode are filtered using the following
criteria (this is what I consider basic TTY emulation):

* All bytes received will get their most significant bit stripped to make 7
bit ASCII characters.

* A "CR" character (carriage return, ASCII 13) will move the cursor to the
first position in the next line.

* A "Backspace" character will erase the last character received and move
the cursor one position to the left, but will never move to the previous
line. The code to be recognized as "Backspace" can be chosen (see "Options
menu"). If TEXT file capture is on, all characters are saved as received in
the file including the "Backspace" characters.

* A "TAB" character (ASCII 9) will be accepted (and saved if TEXT file
capture is on) but displayed as a space character.

* Five consecutive "CAN" (control-X, ASCII 24) are recognized as a signal
to abort text file sends, X/Y-Modem or ZModem file transfers.

* A "BEL" (control-G, ASCII 7) is recognized and if this feature is enabled
via the "Other options..." menu item, the Macintosh will beep. The "BEL"
character is not saved to the terminal buffer or capture file.

* All other control characters are ignored and only characters with ASCII
codes higher then 32 and lower than 126 are accepted (printable
characters).

* If lines longer than 81 (depends on the configured window width)
characters are received a "CR" will be inserted automatically after every
81 characters, and this "CR" will also be saved to disk if TEXT capture is
on.


___________________________________________________________________________
THE "FILE" MENU


SAVE CAPTURE BUFFER

A standard file dialog is presented (if the capture buffer is not empty)
allowing to save the contents of the capture buffer to disk as a TEXT file.
The TEXT file creator can be changed using the "Text capture option" item
in the "OPTIONS" menu. If a modifier key (shift, command or option) is
pressed while selecting the menu option the capture buffer gets appended to
the end of an existing TEXT file.


TEXT CAPTURE

A standard file dialog is presented allowing to create the TEXT file where
all further input or output will be saved. The TEXT file creator can be
changed using the "Text capture option" item in the "OPTIONS" menu. The
menu text will change to outlined and expanded, so that when selected again
the capture file will be closed. The file is also automatically closed when
quitting the program. If a modifier key (shift, command or option) is
pressed while selecting the menu option the capture buffer gets appended to
the end of an existing TEXT file.


TEXT SEND

A standard file dialog is presented to select a TEXT file. The file
contents is sent using the options that can be selected in the "TEXT file
transfer options..." item of the "Options" menu. The menu text will change
to outlined and expanded, so that when selected again the transmission will
be canceled. If five control-X characters are received the transmission is
also canceled.


FILE RECEIVE

If X/Y-Modem is enabled and if Y-Modem batch is active, or if Z-Modem is
enabled, the file transfer starts immediately. During such a session more
than one file my be received. All files received are stored in the folder
selected by the "Binary File Transfer Options" dialog. If MacBinary file
format is enabled, the file name used will be the name from the MacBinary
header if this name does not yet exist, otherwise the name from the Y-Modem
header (block 0) or the Z-Modem file information block will be used, and if
a file with this name exists it is deleted first. If MacBinary is disabled
the file name from the Y-Modem header (block 0), or the Z-Modem file
information block, is used, and if a file with this name exists it is
deleted first.

Note: Z-Modem creates a temporary file while receiving. This file is not
deleted when the Z-Modem transfer is aborted. Instead when the Z-Modem
receive is resumed later on, it will continue were it stopped before. This
partial Z-Modem file has a special file type and a distinct icon. Only when
the receive is complete, will the file type changed to what it should be.

If X/Y-Modem without the batch option (i.e. X-Modem) is chosen a standard
file dialog is presented to create a file to be used for binary file
receive using X-Modem protocol. The X-Modem protocol file receive session
is started. If MacBinary file format is enabled, the file name used will be
the name from the MacBinary header if this name does not yet exist,
otherwise the first chosen name will be used.

Note: For CompuServe QuickB protocol file transfers there is no need for
this menu option as the transfers will be initiated by the host and the
host will prompt you for the file name on your computer. For ZModem receive
there is an option (that can be set in the Z-Modem options dialog) to
automatically start the receive, so the FILE RECEIVE menu command need not
be used.


FILE TRANSMIT

A standard file dialog is presented to select the binary file to transmit
using X/Y-Modem or Z-Modem protocol. If the MacBinary file format is
enabled the file is sent in MacBinary II format. In Y-Modem batch, or
Z-Modem, only one file can be send in a session.

Note: For CompuServe QuickB protocol file transfers there is no need for
this menu option as the transfers will be initiated by the host and the
host will prompt you for the file name on your computer.


MAKE MACBINARY FILE

Use this utility option to create a MacBinary II file from any other file
on your disk. The MacBinary file gets a special file type and a distinct
icon. Normally this operation need not to be used, because the FILE
TRANSMIT menu command will create the MacBinary II file on the fly while
transmitting.


EXTRACT FROM MACBINARY FILE

Use this utility option to extract a file from a MacBinary I or MacBinary
II file on your disk. This is useful if you have forgotten to enable
automatic MacBinary recognition and you have already downloaded a file.


KISS SCRIPT FILE

Use this utility option to change the creator of TEXT files so that the
"Finder" recognizes them as "Terminal" documents. In this way you can
double-click the script file and it will automatically be executed by
"Terminal". Only TEXT files with a file name ending in ".s" can be changed.
To change back the creator of the TEXT file to the creator of the text
editor application, hold down the option key while selecting the KISS
SCRIPT FILE menu command. The creator of the TEXT file will be set to the
TEXT file creator you have set in the OTHER OPTIONS dialog. When you now
double-click the script file, the text editor will open it.


QUIT

To quit and return to the "Finder" use this option or click in the close
box of the terminal window.


___________________________________________________________________________
THE "EDIT" MENU


The first five items are there for desk accessories. Only the following is
used:


PASTE

The text in the clipboard is sent using the options that can be selected in
the "TEXT file transfer options..." item of the "Options" menu. The menu
text will change to outlined and expanded, so that when selected again the
transmission will be canceled. If five control-X characters are received
the transmission is also canceled.


CLEAR CAPTURE BUFFER

This will clear the capture buffer and the terminal window.


SHOW PROGRESS WINDOW

This selects the progress window and brings it to the front. Useful if the
progress window gets covered by other windows.


DEBLOCK SEND

This kills any outstanding serial write request. It might be useful if the
program has received an XOFF, but never got the XON.


NEGATE DTR

This negates the DTR output (output handshake signal).


ASSERT DTR

This asserts the DTR output (output handshake signal).


CHECK CTS

This displays the current status of the CTS input (input handshake signal)
in the status message window.


___________________________________________________________________________
THE "OPTIONS" MENU


The options selected in the following dialogs are saved in a file, so that
they are again available when the program is started at a later time (the
file name is "Terminal Settings"). If no options file is found when the
program is started, default values will be used.


COMMUNICATION

* Port: None, "Modem", "Printer" or any other serial port available.
* Baud rate: 300 to 56700 Baud.
* Data bits: 7 or 8.
* Stop bits: 1 or 2.
* Parity: even, odd or none.
* Handshake: XON/XOFF, CTS only, DTR only, CTS and DTR.

* Don't drop DTR when quitting: useful if you don't want the modem to
hang-up when you quit the program.

Note: During X/Y-Modem or QuickB binary file transfers the data bits are
set to 8 bits. When the transfer is finished the original value is
restored. Z-Modem automatically will escape all characters that use the
high order bit if 7 data bits are used thus enabling binary file transfers
over non-transparent links.


TEXT FILE SEND

* Wait for prompt before sending next line: If this option is checked the
program will wait for the prompt string (this can be more than one
character) before sending the next line while sending TEXT files.

* Delay after each line sent: If this option is checked the program waits
for the specified number of ticks (1/60 second) before sending the next
line while sending TEXT files.

* Delay after each character sent: If this option is checked the program
waits the specified number of ticks (1/60 second) before sending the next
character while sending TEXT files.

Note: the TEXT file send parameters are also used when sending macros or
pasting text from the clipboard.


TERMINAL

* Echo: local (display keyboard characters), remote (retransmit received
characters).

* Display and capture: if checked the capture window and buffer are active,
else nothing is displayed nor captured.

* AutoLF: If this option is checked a linefeed character will be send after
each carriage return character.

* Start-up script: Any script can be selected to be executed automatically
when the "Terminal" application is started.


OTHER

* Text capture file creator: file creator for TEXT files used for saving
the capture buffer or by the "Text file capture" option. So if you double-
click on these files your favorite text editor program is automatically
called. If you un-kiss (see FILE MENU) script files they will get this
creator.

* File type and creator for non-MacBinary files: if automatic MacBinary
file format recognition is not enabled, or if the file received is not a
valid MacBinary file, this type (default is 'TEXT') and creator are used
for the new file.

* Code for "backspace" key: ASCII code send by pressing the "Backspace"
key, and also the ASCII code recognized as "Backspace" code while
receiving.

* Code for "`" key: ASCII code send by pressing the "`" key. This can be
used to make an "ESC" key (ASCII 27) on keyboards that don't have an "ESC"
key.

* Control-G beeps: if checked any "BEL" (control-G, ASCII 7) character
received will beep.

* Control key: the keyboard modifier key to be used for sending control
characters (e.g. cntl-C). On keyboards lacking a "control" key, use either
the "option" key (in this case you cannot send the characters that normally
are only available by using the "option" key) or the "command" key (in this
case you cannot execute menu commands by key equivalent).


BINARY FILE TRANSFER

* MacBinary: use and recognize MacBinary file format in file transfers
(Note that TEXT files are never sent as MacBinary).

* CIS-B: recognize and use CompuServe QuickB protocol for file transfers.
If you don't use QuickB uncheck this option. This makes things faster and
eliminates any false triggering into file transfer mode on noisy lines.

* X/Y-MODEM: use X-Modem or Y-Modem file transfers when using the
"Receive..." or "Transmit..." commands from the FILE menu. Options can be
set in the "XY-Modem Options..." dialog.

* Z-MODEM:  use Z-Modem file transfers when using the
"Receive..." or "Transmit..." commands from the FILE menu. Options can be
set in the "Z-Modem Options..." dialog.

* Auto-receive: when this is checked, Z-Modem receive will start
automatically as soon as a the other side has started transmitting. If you
rarely make Z-Modem file transfers, don't check this. This makes things
faster. The likelihood of false triggering is small, but nevertheless
exists.

* Path for up- and downloads: folder name used for CIS-B up- and downloads
(because the host will only prompt for the file name on your computer but
not the path name), for Y-Modem batch or Z-Modem file downloads (where only
the file name is in the header block).


XY-MODEM OPTIONS

* CRC        If not checked "classic" X-Modem with simple checksum and 128
             Byte blocks will be used. The "1K" options are disabled.
             If checked CRC error checking will be used and the "1K"
             options are enabled.
* 1K off     128 Byte blocks are used.
     aut     128 or 1024 Byte blocks are used automatically and where
             appropriate. During the initial handshaking phase the single
             character "C" is used. This is the "official" way of doing it.
     CK      1024 Byte blocks are used if during the initial handshaking
             phase the two character sequence "CK" is used (this is used by
             Red Ryder 10.3 and perhaps others).
* batch off  No batch protocol is used, i.e. this is X-Modem.
        Y    "Official" Y-Modem batch protocol is used.
        RR   A variant of the Y-Modem batch protocol is used where there is
             no new handshaking phase after the header block (block 0) has
             been sent (this is used by Red Ryder 10.3 and perhaps others).
* timeout    Select the value 5, 10, 15 or 20 seconds.


Z-MODEM OPTIONS

The first three options are used for receive and transmit.

* Escape control characters: if this is checked all control characters are
escaped (including all characters who have their high order bit set). This
slows down Z-Modem but must be used on non-transparent links. In any case,
if using 7 data bits, Z-Modem will ignore this setting and escape all
control characters.

* Timeout (seconds): should be set at 10 seconds.

* Maximal retries: should be set at 10.

The following option is only for Z-Modem receive.

* Receive buffer size (bytes): can be set to 0 or a value between 128 and
32768. If set to 0 the receiver signals to the transmitter that it is able
to receive and save data as fast as it is coming in. Otherwise the sender
will make sure to never have more than this number of non-acknowledged
bytes and waits while the receiver will save the data.

The following options are only used for Z-Modem transmit.

* Transmit sub-packet length (bytes): can be set to 256 for speeds up to
1200 Baud, 512 for speeds between 1200 and 2400 Baud, and to 1024 (maximum)
for higher speeds as recommended in the Z-Modem specifications. The
optimum value depends on the link quality. On good links, 1024 (maximum)
should be used.

* Window limit (bytes): can be set to a value between 0 and 32768. If set
to 0 now transmit window is used. Otherwise the sender makes sure to never
have more than this number of non-acknowledged bytes.

* ZCRQ spacing (bytes): can be set to a value between 0 and 32768. If set
to 0 the sender will not send ZCRQ frames. Otherwise it will send a ZCRQ
frame after having send this number of bytes. ZCRQ frames are used to see
how far the receiver has got, but will otherwise not interrupt the data
stream.

You should consult the Z-Modem specifications to get more details about
these parameters. The default values should be fine for most cases.


___________________________________________________________________________
THE "MACROS" MENU


A macro is a text string kept in memory. There are 10 macro string buffers
available. There is a different menu item for each possible buffer. The
menu item name is the macro name, not it's content. The only limit for the
length of a macro string length is available memory. The command key
equivalents are 0 to 9. When the menu item is selected, or when the
corresponding command key is pressed, the macro string is send out through
the serial port using the parameters that are normally used for sending
text files (prompt string, line and character delays, handshake option). So
macro strings behave like text files, but are kept in memory and can be
send easily with single keystrokes. If you press the option or the shift
key while selecting a macro, the macro string is not send out but simply
displayed in the terminal window. This can be used to test macro sets.

The first menu item is used to load a new macros file using a standard get
file dialog. A macros file is a simple TEXT file with a ".m" suffix, that
contains a complete set of macros, up to 10 different macros. This text
file can be created and edited with any TEXT editor. If there exists a file
named "Macros.m" in the script folder it will be used automatically when
the Terminal program is started. The contents of the macros file must
respect the following rules:

* Macro names start with the two characters "\m" (or "\M") and continue
until the end of the line. They will get truncated to 30 characters in the
"Macros" menu.

* All the text following a macro name becomes the macro text, including any
line returns, they are translated to carriage return characters. The macro
text stops one character before (the last character, usually the final line
return, is not included) the beginning of a new macro name, or at the end
of the file. The only limit for the length of macro text is available
memory.

* To include the backlash character in macro text use the two character
sequence "\\". To include control characters, other than the carriage
return which is the same as control-M, use the two character sequence "\x",
where "x" is the control character to use. E.g. to include control-C use
"\C" (or "\c").

* Macros found in the macros file will get numbered automatically starting
at 0. Macro numbers not used will get disabled in the menu.

See the included examples of some macro files to see how they might look
like.

Note: the macro files to be loaded by the script function "macrol" must be
in the "Terminal folder".


___________________________________________________________________________
THE "SCRIPTS" MENU


A script is a TEXT file containing a program written in "Terminal" script
language, which is a subset of the C language. Scripts are interpreted by
"Terminal", there is no compilation step involved. The easiest way to
maintain scripts is to use a desk accessory TEXT editor. If you use a word
processor, you must save the script files as pure TEXT, not in the native
format of the word processor.

The first item in this menu can be used to select any script file on your
disk using a standard file dialog box. Only TEXT files with a suffix of
".s" are considered to be scripts.

The other items depend on what "Terminal" found in it's folder when it was
started. If a folder "Terminal Folder" exists in the application folder,
all script files found there are included in the menu. If no such folder
exists all script files found in the application folder are listed in the
menu. Selecting a script in the menu will start it. The menu item name
changes to outlined and expanded. To cancel a running script simply select
it's menu item again. If a script is running the terminal window's name is
set to the name of the executing script.

Only one script at a time can be executing. Any script can be selected to
execute automatically when "Terminal" is started by using the "Terminal
Options" menu. You can also double-click script files from the Finder, if
they have been "kissed" before (see FILE menu commands). They are
automatically opened and executed by "Terminal".


___________________________________________________________________________
THE SCRIPT LANGUAGE


The script language interpreted by "Terminal" is a subset of C with many
specialized intrinsic (built-in) functions. Please read a C reference book
to learn the C syntax, or see the enclosed script examples to get a feeling
of the language. I will not write a book about programming in C here, only
tell you the essentials.


PROGRAM

A program is recognized as a script if it is in a TEXT file, and if the
file name ends in ".s". Spaces, tabs and carriage return characters are
considered to be white space. No identifier and no keyword can be separated
by white space. A program consists of: comments, global variable
definitions and function definitions. Everything included between "/*" and
"*/" is considered a comment and will not be interpreted. Comments cannot
be nested. The "/*" and "*/" are not recognized as comment delimiters
inside string or character constants. Global variables are those variables
that are known to all functions, unless their names are reused as local
variables. Global variables can be initialized using any expression that
involves either constants or other globals that are already defined at that
point. Function definitions can appear in any order and their must be at
least one function called "main" with no parameters. It is this function
that is called when the script is started. Every function is supposed to
return an integer value as result. If there is no return statement in a
function, 0 will be returned. Functions can be called recursively. There
are many built-in functions that are already defined when the script is
started.

The value the "main" function returns is used as follows:
      0 : Don't restore saved settings, continue application
      1 : Restore saved settings, continue application
    256 : Don't restore saved settings, quit application
    257 : Restore saved settings, quit application
Restore saved settings means that all changes the script made to settings
are forgotten as soon as the script finishes. Quit application means, that
as soon as the script has finished, "Terminal" quits. Usually this means
returning to the Finder. But if "Terminal" was launched from HyperCard it
will return to HyperCard.

This is an example of a simple script that displays the message "The number
is 123" in the terminal window:

    int Number = 123;   /* This is a global variable */

    main ()     /* Every script must have a main() function */
    {
        /* display() is a built-in function */
        display("The number is %i\r", Number);
    }


IDENTIFIERS

An identifier is a sequence of letters and digits; the first character must
be a letter. The underscore "_" counts as a letter. An identifier can be of
any length up to 255 characters. All characters are significant and are
case sensitive. There are three types of identifiers: keywords, function
names, variable names. The keywords are: "break", "char", "else", "for",
"if", "int", "return", "while".


CONSTANTS

An integer constant is a sequence of decimal digits, or 0x followed by up
to 8 hexadecimal digits. An integer value is represented internally by 4
bytes (32 bits). A minus sign before a constant is considered as an unary
operator, not a part of the constant itself. A character constant is a
sequence of 1 to 4 characters enclosed in single quotes. Character
constants are converted to integer values, the byte values corresponding to
the ASCII codes of the characters. A string constant is a sequence of
characters enclosed in double quotes. String constants are automatically
terminated by a NULL character. The value