Atari 400 Basic Reference Manual

DIM (DI.)
8
ARRAYS AND
MATRICES
An array is a one-dimensional list of numb ers assigned to subscripted va riables ;
e.g., A(O), A(1), A(2). Subscripts range from 0 to the dimensioned value. Figure
8-1 illustrates a 7-element arra y.
A(O)
A(1)
A(2)
A(3)
A(4)
A(S)
A(6)
Figure 8-1. Example of an Array
A matrix, in this context, is a two-dimensional table co ntaining rows and col-
umns. Rows run horizontally and columns run v erticall y. Matrix elements are
stored by BASIC in row -m a jor order. This means that a ll the e lem ents of the
first row are stored first, followed by all the elements of the second row, etc .
Figure 8-2 illustrates a 7 x 4 matrix.
Columns
M(O,O) M(0,1) M(0,2)
M(0,3)
M(1,0)
M(1 ,1)
M(1,2)
M(1,3)
M(2,
0) M(2,1)
M(2,2)
M(2,3)
M(3,
0) M(3,1)
M(3,2)
M(3,3)
M(4,0) M(4,1) M(4,2) M(4,3)
M(5,
0) M(5,1) M(5,2) M(5,3)
M(6,0) M(6,1) M(6,2)
M(6,3)
Figure 8-2. Example of a Matrix
This section describes the two commands associated with arrays, matrices, and
strings, a nd how to load both arrays and matrices. The com~a nds in this se c-
tion are:
DIM
CLR
Format:
D M { svar(aexp) }
1
mvar(aexp[ ,aexp])
IJ{ ,svar(aexp) }tl
~ ,mvar(aexp[ ,aexp ... ] U
Examples: DIM A(100)
DIM M(6,3)
DIM B$(20)
used w ith STRINGS
An a ,v s and Matr·ices 41

Atari 400 Specifications

General

Manufacturer	Atari
Model	400
Type	Home Computer
Release Year	1979
CPU	MOS Technology 6502
CPU Speed	1.79 MHz
ROM	10 KB
Operating System	Atari OS
Keyboard	Membrane keyboard
RAM	8 KB (expandable to 48 KB)
Graphics	ANTIC and GTIA chips
Sound	4 channels
Display	RF output for connection to TV
Storage	Optional cassette tape drive or floppy disk drive
Ports	Cartridge
Display Resolution	320x192 (16 colors)