APPENDIX NINE _____________________________________________________________



Numerical Conversions

If you use this map a lot, or use the Atari a lot for machine language
routines, interrupts, graphics and the like, you know the need to
translate between decimal and hexadecimal, even back and forth with
binary, frequently. It is possible, although tedious, to do your
translations by hand, using pencil and paper. The tables for doing so
are below. It's not the best nor the fastest method available. I
recommend you get the Texas Instruments TI Programmer calculator.
It does most of this work for you, plus bit manipulation (unfortunately it
does not offer binary translation). It's an indispensable tool for
programmers.

There are other ways around buying the calculator: you can buy
Monkey Wrench from Eastern House Software, which will do the hex -
decimal translations for you quite nicely. Or you can buy any of the
numerous disk or programming utilities which include such translation
routines, such as Disk Scan from Micro Media. However, those who
wish to do the work themselves can use a simple translator program.
One such example, modified from routines that appeared separately in
COMPUTE!, November 1981 and March 1982, is:

10 DIM HEX$(16),DEC$(23),NUM$(10),W$(
   4),BIN$(8),BNY$(8),TRANS(8)
15 DATA 128,64,32,16,8,4,2,1
20 FOR N=1 TO 8:READ B:TRANS(N)=B:NEX
   T N:POKE 201,14
25 PRINT CHR$(125)
30 HEX$="0123456789ABCDEF":DEC$"=@ABC
   DEFGHI!!!!!!!JKLMNO"
40 ?:?"PRESS [OPTION] FOR HEXADECIMAL":
   ?"{6 SPACES}[SELECT] FOR DECIMAL":?"
   {6 SPACES}[START] FOR BINARY"
42 ?"{6 SPACES}TRANSLATIONS":A=1:MAX=
   4096 
50 IF PEEK(53279)=3 THEN GOTO 100
60 IF PEEK(53279)=5 THEN GOTO 200
70 IF PEEK(53279)=6 THEN GOTO 300
80 GOTO 50
100 ? : ?"ENTER HEXADECIMAL NUMBER":"?
    "$0000 TO $FFFF": INPUT NUM$:ACC=
    0:A=1:TRAP 100
120 FOR NUM=1 TO LEN(NUM$):ACC=ACC*16
    +ASC(DEC$(ASC(NUM$(NUM))-47))-64:
    NEXT NUM:T=ACC