ZX81 Listing for enlarger.p


ZX81 program listing for *ENLARGER ASM**SLR/22*

*ENLARGER ASM**SLR/22* (enlarger.p)

The original enlarger was a simple BASIC program that demonstrated how to enlarge an object, but was horribly slow. This is the assembler version that drastically improves the speed and adds a couple more pictures.


SYSTEM VARIABLES

PROG  : 16509
D-FILE: 18547
VARS  : 19340
E-LINE: 19341
STKBOT: 19346
STKEND: 19346


LEGEND

9999 means line number
PRINT means treat as KEYWORD P


PROGRAM LISTING

   1 REM /*ENLARGER ASM**SLR/22*
30413 LN Eú51INKEY$LN GOTO RND5
THEN INKEY$LN GOTO RND5N?LN
GOTO RND5RND3LN 7INKEY$5 THEN
INKEY$LN ?INKEY$ñ  LN PRINT !5
ACS ?LN GOTO RND5RND3LN 7INKEY$5
9PILN ?INKEY$5RND3LN 7INKEY$5??
LN ?INKEY$5RND3LN 7INKEY$?2RND/
SAVE GOSUB RND<5??ñCHR$ ò
GOSUB KTAN )??E£RNDCHR$ ò
GOSUB KTAN )5?5PI?Y+ñ5 GOSUB SX
TAB *INKEY$TAN   65INKEY$LN VòGC
)H??LN X÷BASN >=£TAN E5INKEY$F?P
4 THEN TAN LN VòG4IF TAN )??E£
RND7ö"VAL ö(VAL ?ñ4 ù?7?LPRINT 7
7FOR AT (REM ñ) ùFOR ñ6 ùFOR AT
( AND ?POKE RNDFAST LN LPRINT
LN GOTO RND5POKE ñLN 7INKEY$öõ
VAL LN ?INKEY$5POKE ñLN 7INKEY$
AT (NEXT TAN WE SHALL ENLARGE A 
PICTURE OF A MOON.              
             COPY               
                  
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32896                            
 
32896                            
 
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65408                            
  
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32896                            
 
   8 !                          
 
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32768                            
 
65332  TO ENLARGE THE MOON WE WIL
L TAKE EACH SQUARE AND MULTIPLY 
ITBY 4 MAKING A LARGER PICTURE. 
                                
  PRESS ENTER TO BEGIN...COPY TH
AT WAS A SCALE ENLARGEMENT OF A 
MOON.  NOT VERY SPECTACULAR,  BU
T, IF ONE COULD MODIFY THIS   SI
MPLE PROGRAM, THE EFFECT COULDBE
 BOTH USEFUL AND SPECTACULAR.
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30208  RAND USR VAL "16514"