LDW BASIC Compiler for Atari ST. The first few pages of the manual have been torn out of binder but the rest is fine.
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The LDW BASIC Compiler is a compiler for programs written in ST BASIC that also implements a number of enhancements. A compiler converts a program into machine code, so the final result of the LDW compiler will usually run many times faster than the interpreted ST BASIC version could.
There are two reasons why many people prefer interpreters over compilers. First, a compiled program must normally be written, compiled and tested; if anything doesn\'t work properly (usually the case), you must go back to your original program, correct it and recompile--a process that can be very lengthy. Second, it can be very difficult to find the problem in a compiled program, since you can\'t just print out the values of variables to see what is going wrong. To get at variable values, you must build debugging statements into your program to print them out, then remove those statements after the program is working.
The LDW BASIC Compiler gets around these problems by compiling ST BASIC. Thus, you can write a program in interpreted ST BASIC and debug it; once everything works properly (but slowly), you can compile to produce a fast version. Although you may not get exactly what you want the first time (it may be toofast), the amount of back-and-forth debugging is kept to a minimum.
Since the LDW BASIC Compiler is designed specifically to compile ST BASIC, it has most of the same drawbacks, except speed. Some enhancements have been built-in: line numbers are optional, and the constraints on array and string size as well as number of lines, have been removed; there\'s double-precision math, and a multiple-pairs version of LINEF lets you draw many lines using one command. Of course since these enhancements are not available in ST BASIC, you will have to go back to the compile-debug-fix cycle if you want to use them. A very few normal ST BASIC commands do not work in the compiler, but they are well documented and not likely to cause trouble.
The newest version of the LDW compiler, revision 1.1, adds many new commands including some to read and set the time and date, enable and disable the break key ([Control] [C]), and enable the output window. Unlike the original version, it has no copy-protection, and it includes a variety of batch files for compiling and linking your ST BASIC program. Also available is the option to not produce the assembler source code, which saves a great deal of time and disk space. Using a RAMdisk or hard disk cuts the time required still further. One of the batch files for two-drive systems allows you to simply walk away and come back later to find everything done, with the .PRG file on your disk.
Another enhancement is the inclusion of GEM bindings--subroutines that do all the dirty work of calling GEM and AES for you. For example, to create an alert box you simply set two variables and GOSUB FORM_ALERT. The subroutine will even return the number of the button in the alert box you clicked on. The use of the GEM bindings is muchmore straightforward than POKEing and PEEKing in ST BASIC. The bindings are well documented, noting what variables must be set and what they are and what special arrays must be dimensioned; the documentation includes page numbers in Atari\'s GEM manuals and Abacus Software\'s Atari ST GEM Programmer\'s Referencefor finding further information. The GEM bindings will even work in regular ST BASIC programs, and they are a valuable addition to the LDW package\"
