Atari 800 Basic Reference Manual

2. Now add the BASIC language part of your program starting at line 1080 in-
cluding the USR function that calls the machine language subroutine. (See
example below.)
3. Count the total number of hex codes to be entered and enter this number on
line 1000 when requested. If another number is already entered, simply
replace it.
4.
Run the program and enter the hexadecimal codes of the machine level
subroutine pressing 1Di1J after each entry . After the last entry, type
DONE and press IDiiJ.
5. Now the DATA line (1500) displays on the screen. It will not be entered into
the program until the cursor is moved to the DATA line and fiiiim is
pressed.
6. Add a program line 5 GOTO 1000 to bypass the hexcode loader (or delete the
hexcode loader through line 260). Now save the completed program by
using CSA VE or SAVE. It is important to do this before executing the part of
the program containing the USR calL A mistake in a machine language
routine may cause the system to crash. If the system does hang up , press
(ftii@l;li!+ii . If the system doe sn't respond, turn power off and on again,
reload the program, and correct it.
Note: This method only works with relocatable machine language routines.
The following two sample programs can each be entered into th e Hexcode
Loader program. The first program prints NOTHING IS MOVING while the
machine program changes the colors. The second sample program displays a
BASIC
graphics design, then changes colors.
1980 GRAPHICS 1+16
1090 FOR I=1 TO 6
1100 PRIHT #6j
11
t10t.hir.s is t"II0
1
v
1
in::t!
11
1110 PF~INT #6;
11
t~OTHH~ IS t10UH~G! II
1120 PRIHT #6.:
11
not.hins ls mo
1
... •ins!
11
1130 PRIHT #6.:
11
NOTHit·~ IS t101...!H~G! II
1140 NE:)::T I
1150 Q=USR( ADR< E$ )+ 1 )
1160 FOR I=1 TO 25: t· E=<T I = GOTO 1150
After entering this program, check that line 1000 reads:
1000 CLR:BYTES
= 21
Type RUN liimmJ.
Ad vanced Progra mmin g Techn iqu es 65

Atari 800 Specifications

General

Processor	MOS Technology 6502
Processor Speed	1.79 MHz
ROM	10 KB
Graphics	ANTIC and GTIA chips
Release Year	1979
Display Resolution	up to 320 x 192
Colors	128 colors
Sound	4 channels
Storage	Cartridge, cassette, floppy disk
Ports	Cartridge, serial, monitor
Operating System	Atari OS