Atari 400 Basic Reference Manual page 73

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 doesn '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 the 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.
Advanced Programming Techniques 65