LLUCE/SOURCE/DATA/CHANGES

L & L  Universal Communications Environment (LLUCE)

This document was prepared by Andrew Wells on November 27, 1992.

This is mostely just a list of the differences between LLUCE and ACOS,
comparing LLUCE with a system that a lot of people already are familiar with.

LLUCE has been long in coming, but I think those who have had the patience to
wait won't be disappointed.  I have spent many hours, days, etc. putting
everything I and others could think of into it without making it so big that it
wouldn't fit within a 128k environment.  I also didn't want to take so much
time adding stuff that wouldn't get used (at least not much), like arrays, that
it take even longer to release, and would tend to slow it down too.

This is a list of what LLUCE has evolved into.  We wanted to stay fairly close
to the ACOS syntax so as to not confuse some of the less programming literate
BBS owners out there, but we also wanted to make it as useful, as fast and as
close to some of the accepted language standards out there.

The following is a list of the major changes.  Minor bug fixes aren't listed
here, but you can be sure that all reported bugs have been taken care of along
with quite a few that no one ever came across..

Source/Compiler
---------------
- The compiler is more than 1500% faster than ACOS was.  What this means is
  that a segment which would take 2 minutes, 45 seconds with ACOS, when
  converted to LLUCE syntax (probably making it a slight bit larger) will take
  only 10 seconds to compile with LLUCE.
- In line/multiple line (block) comments work same as pascal { }
- Line continue character allows more free-form coding.
- LLUCE and ACOS both allow 8 public labels per segment.  ACOS did no checking
  at all (other than the label exists) on the number of labels, LLUCE shows an
  error message (but continues compiling).  Also, only those labels that are
  designated as public are available from outside of the segment (ACOS allowed
  the first 8 labels declared)
- Variable names may contain as many as 4 signifigant characters.  The compiler
  will only place as many characters as are needed in the compiled code
  (A$ with ACOS used 3 bytes, the string designator, the A and a space, LLUCE
  uses the string designator and just the A)

EXTERNAL stuff
--------------
- Allows shell programs to insert pathnames
- CRC16 routines are built in
- Overlays are only loaded if they haven't been loaded, or have been corrupted
- Added read/write multiple bytes routines
- DCI string print routine is callable from overlays
- Variables can be stored and recalled by overlays
- A routine is available that sets the current prefix to the SYSTEM prefix.
  This is where all LLUCE system modules (Compiler, Editor and overlays) are
  kept.

Optimizations/Changes
---------------------
- Support for 3 disk files (one more than ACOS)
- Full 24 bit arithmetic and variables
- There are now 4 256 byte RAM areas instead of just 2 64 byte RAM areas
- DriveSpecs are GONE!  Standard ProDOS pathnames are now used throughout

Existing command changes
------------------------
- The INSTR function has been changed to allow an optional starting position
- DATE$ and WHEN$ work with any year
- WHEN$ lets you use any date, not just the current date
- The NEXT command will allow the use of a variable to abort inner loops
- Major syntax changes have been made to all those functions that required a
  number for a parameter (eg MODEM(0)).  The syntax is more descriptive now
- CREATE has been changed to be able to create directories and message files
- FLAG, NIBBLE, BYTE, WORD, FILL, MOVE, READ and WRITE will accept position
  or count parameters greater than 255
- OPEN command allows a READ or WRITE parameter for network file access.  If no
  READ or WRITE parameter is used, files are opened for READ/WRITE access.
  If there is no AppleTalk network available, the access parameter is ignored.
- The LINK command was changed to CHAIN.  LINK could mean several things

New commands added
------------------
- ON ERROR GOTO and RESUME commands
- WORD function (like FLAG, NIBBLE and BYTE that ACOS has, but uses 2 bytes)
- TIME12$ can be used to get time in 12 hour format
- EDIT ON/OFF turns profanity filter on or off
- ON x GOSUB, ON x GOTO and ON x PUSH commands
- RTRIM$ and LTRIM$ string trim commands
- UPPER$, LOWER$ and MIXED$ string case conversions
- FLASH enables or disables GS screen color changes
- WINDOW function to set window boundaries (not fully implemented, needs
  rewritten video driver)
- EXIST was added to check if files exist on disk
- LOCK, UNLOCK and RENAME are built in
- TYPE was added to support files other than straight text (SRC, AWP)
- The USE command was removed.  In it's place is OVERLAY.  Not only do overlays
  load and execute in a different location than the ACOS USE files, but they
  don't disturb the editor buffer, and their format is slightly different - see
  Security below.
- PREFIX was added to support ProDOS pathnames
- Many terminal emulation commands were added.  These can be used in several
  ways.  You can use them to generate terminal control characters, or you can
  set or read the values of the terminal control codes.

Security
--------
- All overlays are checked with CRC16 and ID code for validity
- The main LLUCE code is checked for valid CRC before running to insure it's
  integrity

Messages
--------
- Message system allows 4 MSG numbers instead of just 1
- MSG numbers are 24 bit numbers
- Removed text compression/decompression so 8 bit ASCII can be used

Editor
------
- Editor hack line was changed from ^T to ^Y (per HIN)
- Added support for normal, inverse and moustext
- More than one editor is possible.  The name of the editor to use can be set
  to any editor in the LLUCE system directory

Miscellaneous
-------------
- Waiting for call uses 2 flashing apples and current time to show it's active.

- Screen saver is built in, and is active while waiting for calls
  The screen will blank on //e, and the screen will change colors on GS
  The screen saver timeout value can be set where you want it

- The filename processor will change any illegal characters to periods (.)

- The NIBBLE command stored nibbles backwards in ACOS.  This would result in
  problems if you wanted to set values with nibbles and read them back as FLAGs
  or BYTEs (and now WORDs).  For example, you have BYTE and NIBBLE set to RAM,
  then set NIBBLE(0)=1, NIBBLE(1)=0.  What you should expect from a
  PRINT BYTE(0) would be a 1, but with ACOS, you'd get a 16, and that isn't the
  way it should be.

- LLUCE allows commands to be sent to the modem, so a terminal program could be
  written that supports dialing.