Tricks in BASIC

[XavSnap]

To set or retrieve a binary value in memory:

To retrieve the D_file:
10 LET A=PEEK 16396+256*PEEK 16397

Code: Select all

1 REM [HEX: 2A,32,40,4E,23,46,C9 ]
10 RAND 16396
20 LET A=USR 16514

;------- TASM ASM mnemonics. -------
;------- ROM and RAM Symbols -------
RAM_SEED equ $4032

ORG 16514
Start:
	LD HL,(RAM_SEED) ; GET SEED
	LD C,(HL) 
	INC HL 
	LD B,(HL) 
	RET ; ==========================
.end

To POKE a decimal value:
10 POKE 16507,A-INT(A/256)*256
20 POKE 16508,INT((A/256)

Code: Select all

10 RAND A
20 POKE 16507,PEEK 16434
30 POKE 16508,PEEK 16435

Have fun.

[XavSnap]

How to get a character code with a PRINT AT ?

Code: Select all

10 PRINT AT Y,X;
20 IF PEEK (PEEK 16398+256*PEEK 16399)<>0 THEN GOTO xxxx

This code peeks up the next character after the X,Y coordinates.

In ASM:

RAM_DF_CC equ $400E

ORG $4082 ; [@16514/@h4082]
Lb4082:
LD HL,(RAM_DF_CC) ; GET DF-CC (NEXT CHARACTER PRINTED LOCATION)
LD C,$00
INC HL
LD B,(HL)
RET ; ==========================

Code: Select all

     0 REM [HEX: 2A,0E,40,0E,00,23,46,C9 ]
     10 PRINT AT Y,X;
     20  IF USR 16514<>0 THEN GOTO xxxx

[XavSnap]

Booleans in BASIC:

Code: Select all

  5 LET FALSE=0
  7 LET TRUE=1
  9 LET B=0
  10 LET A=TRUE
  20 IF A>0 THEN LET B=B+1
  30 LET B=B+1*(A>0)
  35 LET B=B+(A>0)
  40 LET B=B+NOT NOT A
  45 PRINT "A IS ";("TRUE") AND A;("FALSE") AND NOT A,,,,
  50 PRINT "BOOL SUM=";B
  

[XavSnap]

"ON N GOTO 1250,2000,4500,6001,2000,4500,6001"

IF you can't use a GOTO N...

Example:
#Regular code:

Code: Select all

10 IF N=1 THEN GOTO 1250
20 IF N=2 THEN GOTO 2000
30 IF N=3 THEN GOTO 4500
40 IF N=4 THEN GOTO 6001
50 IF N=5 THEN GOTO 2000
60 IF N=6 THEN GOTO 4500
70 IF N=7 THEN GOTO 6001
80 STOP

Use this code:

Code: Select all

110 GOTO VAL"1250200045006001200045006001"(N*4-3 TO N*4)

[XavSnap]

Compess the D_file in 1,2 or 16k:
Set the RAM_TOP TO 1k or 2k:

ZX81: (1K)
POKE 16389,68
NEW

TS1000: (2K)
POKE 16389,72
NEW

Or in 16k BASIC (only 22 lines)

Code: Select all

1 PRINT "HELLO"
2 STOP
10 FOR A=1 TO 22
20 SCROLL
30 NEXT A
60 SAVE "P"
70 RUN

[XavSnap]

Hi,

In BASIC, after a FAST/SLOW process, an unsightly scrolling can occur when exiting the FAST mode.

To avoid this dropout of the screen frame, just add a PAUSE before the SLOW commande:

Code: Select all

10 FAST
(... your code..)
1000 PAUSE 0
1010 SLOW

Have fun.

[stroebeljc]

Hi,

In BASIC, after a FAST/SLOW process, an unsightly scrolling can occur when exiting the FAST mode.

To avoid this dropout of the screen frame, just add a PAUSE before the SLOW commande:

Code: Select all

10 FAST
(... your code..)
1000 PAUSE 0
1010 SLOW

Have fun.

...and don't forget to add this line if running on first editions ROMs:

Code: Select all

1005 POKE 16437,255

[stroebeljc]

I love your suggestions, XavSnap.
You're such a trickster!