Tech Tips

BY BILL MARQUARDT, ANTIC TECHNICAL ASSISTANT

AUTOBOOT BASIC

To make your favorite BASIC program run automatically when you boot your Atari, rename it AUTORUN.BAS. Then RUN the following program which will create an AUTORUN.SYS file on the same disk.

We found this listing in the February 1987 issue of Pan*Atari* News, from the Panama Canal Atari Users' Group.

10 OPEN #4,8,0,"D:AUTORUN.SYS"
20 FOR I=1 TO 94:READ A:PUT #4,A
30 NEXT I:CLOSE #4:END
40 DATA 255, 255,0,6,81,6,216,24, 173,48,2,105,4,133,204,173,49,2,105,0,133, 205 ,24 ,160,0,177,204,105,162,133,212
50 DATA 160,1,177,204,105,0,133,213,160,32,185,49,6,145,212,136,208,248,169, 13, 141, 74,3,96,0,48,47,43,37,0,24
60 DATA 20,18,12,17, 18,26,50,53,46,0,2,36,17,26, 33,53,52,47,50,53,46,14, 34, 33, 51, 2,226,2,227,2,0,6

The following two Tech Tips were sent in by Texan James Hague, author of Uncle Henry's Nuclear Waste Dump (Antic, December 1986).

[BREAK] KEY TRAP

Sometimes you prefer your program to detect the [BREAK] key when it is pressed, instead of simply disabling [BREAK] entirely. The following short program is an example of how to do it.

10 FOR A=0 TO 6: READ B:POKE 256+A,B:NEXT A
20 POKE 566,0:POKE 567,1
30 DATA 169,1,141,7,1,104,64
40 POKE 263,0
50 IF PEEK(263)=0 THEN 50
60 ? "BREAK WAS PRESSED": GOTO 40

RAINBOW STRIPES

Here is a variation of the famous Atari "rainbow effect" created by display list manipulation. With this program, pressing any keys on your Atari keyboard will produce a different effect. Remember that [SHIFT]ed and [CONTROL]led keypresses are different.

10 FOR A=0 T0 14:READ B:POKE 1536+A,B:NEXT A
20 A= USR(1536)
30 DATA 200,152,74,45,9,210,141,10,212,141,24,208,76,0,6

ROTATE FIX If you tried and failed to get Rotate-from the February, 1987 Tech Tips to work, here is the fix:

1. Change the 2317 in line 40 to 217.
2. Change the 233 in line 40 to 223.
3. Change the 4C in line 70 to 40.
4. Change the 102 in line 80 to 1024.

BIG SCREEN

The following program was written by David Pochron and appeared in the March, 1987 issue of Florida's Atari Journal. It will create a 48 X 28 character display in GRAPHICS 0 mode by altering the display list and using the wide screen mode. A suggested use for this technique is in VCR applications, such as creating title screens. Note that printing to the "forbidden zone" requires extra programming, as in line 140 of the sample program, because the operating system is not set up for the extra space.

10 MEMTOP= PEEK(106) * 256
20 DL=1536:REM NEW HOME FOR DISPLAY LIST
30 TRAP 40:FOR I=DL TO DL+34:READ D:POKE I,D:NEXT I
40 DATA 66,0,0,2,2,2,2,2 2,2 2 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,65,0,6
50 SCSIZE= 28 * 48
60 SCMEM=MEMTOP-SCSIZE:REM GET START ADDRESS OF NEW SC R E E N
70 HB= INT(SCMEM/256):LB=SCMEM-256*HB
80 POKE DL+1,LB:POKE DL+2,HB
90 POKE 88, LB: POKE 89,HB:REM TELL THE O.S. WHERE THE SCREEN STARTS
100 POKE 560,0:POKE 561,6: REM TELL THE HARDWARE WHERE THE DL IS
110 POKE 559,35:REM SET SCREEN TO WIDE MODE
120 POKE 82,0:? CHR$(125):REM LEFT COLUMN IS o; CLEAR SCREEN
130 POSITION 0,5:? "This is now a borderless screen! :POSITION 0,10
135 DIM A$(40):A$="THIS IS THE INACCESSIBLE AREA"
140 FOR I=0 TO LEN(A$)-1:POKE SCMEM+5+1+25*48,ASC(A$(I+l))-32:NEXT I

If you have a Tech Tip that you would like to share with other readers, send it along to Antic Tech Tips, 544 Second Street, San francisco, CA 94107. You might get your name in print. We always welcome very short programs that demonstrate the Atari's powers, simple hardware modifications, or useful macros for popular software.