Atari XL User Manual

Advanced Techniques
DESIGNING GOOD PROGRAMS
201
It is easy to write simple BASIC programs, and
after some practice you will find it fairly easy to
write quite complicated routines. However, unless
you plan your programs carefully, a long program
can get very messy and it can be very difficult to
find all the mistakes you are bound to make.
To write complex programs successfully you must
design them carefully, following a few simple rules.
The phrase structured programming is often used
to describe these rules ; all this means is that
programs designed in accordance wi th these rules
have a clear and logical structure, and the flow
through the program is easy to follow . You may be
put off by hearing people say that BASIC is not a
suitable language for structured programming.
Don't let this discourage you. While BASIC may
lack the elegance of some other languages, it is still
possible to use it to write good programs by
following the simple guidelines set out here:
1 Always plan out the program on paper. Decide
what you want the program to do, identifying
the various tasks it will have to perform, and
divide the program into sections which
correspond to the tasks. For example, you
might have one section of program to get data
from the keyboard, another to sort the data, a
third to display results, and so on.
2 It is often useful to draw sketches of the way the
tasks fit together.
When you have got the overall structure of the
program sorted out, work out in more detail

Atari XL Specifications

General

Release Year	1983
CPU	MOS Technology 6502C
Graphics	ANTIC, GTIA
Sound	POKEY (4 channels)
Storage	Cassette tape
Ports	Cartridge
Operating System	Atari BASIC
CPU Speed	1.79 MHz
RAM	64 KB