AstroBASIC Variables, Commands and Functions list
  Ver. 1.01 by Richard C. Degler - re-typed 9/9/2019
 
 
VARIABLEs are Words that can freely be Read AND Written to -
  In computer-ese, Bytes are 8-bits wide and can hold 0 to 255.
  Words are 2 consecutive Bytes long, and can have data values 
  equivalent to decimal -32768 thru 32767 using one bit as Sign.
 
  26 One-letter Read/Write Storage-only full-Word Variables :
A  [now located at %(20002)  note: see '%' below]
  and runs in alphabetical order by 2's up through to
Z  [at %(20052) decimal]  making %(20054) the following] :
 
  note: In Bally Basic (updated to Astro Basic), _device_ Words
  also control and report on the various parts of the hardware -
 
  6 Two-letter old BallyBasic Read/Write _device_ Variables :
BC  [Background Color] - default 7 White
FC  [Foreground Color] - default 0 Black
NT  [Note Timer] - default 2 (was 3 in BB)
CX  [Cursor X position] - default -77
CY  [Cursor Y position] - default 40
XY  [XY position] - from last LINE command
 
  12 new Two-letter AB _device_ Variables (except for ReMainder) :
MO  [frequency of Master Oscillator] - 71
TA  [frequency of Tone A] - oscillator A used for Notes
TB  [frequency of Tone B] - osc B default 0, 255 max
TC  [frequency of Tone C] - osc C default 0, 255 max
VR  [Vibrato modulation Range] - depth 0 to 63
VF  [Vibrato changes Frequency] - rate 0 to 3
VC  [Volume of voice C] - default 0, 15 max
NM  [Noise Mode] - 2-bits Vibrato if 0, Noises 1 to 3
VA  [Volume of voice A] - default 0, 15 for a Note
VB  [Volume of voice B] - default 0, 15 max
NV  [Noise Volume] - default 0, to 15 max
RM  [ReMainder] - from last divide (as in BB)
SM  [screen text Scroll Mode] - new for AB as listed ...
  SM=0 - Scrolls conventionally [at bottom of screen, as in BB].
  SM=1 - Suppresses scrolling, cursor stays at bottom line
  SM=2 - Holds cursor at screen bottom, clears after each CR
  SM=3 - Clears the screen and resets cursor to screen top.
  SM=4 - AUTO-PAUSE, release by pressing any key. After release
  the screen will clear and printing will resume from screen top.
 
  a direct Word read / write [ =%() or %()= ] on a Byte boundary :
%(+nnnnn)  [from 0 to 32767 see: Memory Map for address ranges] or
%(-nnnnn)  [to -32768 Interlaced Data at -nnnnn times 2 AND 65535]
 
  2 overlapping Variable Arrays following Program :
@(0 to SZ/2) - AT-Array Words ascending from TXTUNF+4
*(SZ/2 to 0) - Star-Array Words descending from DFTLMT
  TXTUNFilled and DeFineTextLiMiT are known by their SZ difference!
 
 
COMMANDs cause an effect based on their Parameters -
 
  2 Commands to Output a single Character :
TV=  [TeleVision] - to Virtual Display Monitor
MU=  [MUsic] - Play a Note to Speaker ONLY
 
  a new Command for AB to Mute all Sounds :
'down-arrow' [entered as 'BLUE' then '3' on the keypad]
 
  a Command to Output a Byte to ...
&(0 to ??)=  [to any OutPort directly]
 
  15 WORD-shifted Commands :
LIST (optional Start line)(optional ,Number of lines)
CLEAR  [reset VDM screen] - "WHAT?" if any arguments
RUN  [re-initialize and go around again] - no arguments
NEXT  [if Var. matches FOR loop, add STEP, exit if greater]
LINE X,Y,T  [draw vector to new X,Y location in Type 0 to 3]
IF  [if Comparison (see below) is False, bail to next Line]
GOTO  [abandon current position and go to new Line given]
GOSUB  [save current position and go to new Line given]
RETURN  [no arguments, just goes back to latest GOSUB]
BOX X,Y,W,H,T  [draw a BOX from origin, +/- sizes in Type 0-3]
FOR (optional STEP) [followed by TO] - mark the top of a loop
INPUT (optional "String") Variable [PRINTS a ':' then inputs]
PRINT (optional '#'Sizes) "Strings", Expressions, or Commas]
 
  Comparisons for IF and any other 0/1 False/True decisions :
>=  [is relatively Greater than or Equal]
#  [Left side is Not Equals Right side]
>  [is relatively Greater than]
=  [Left side is Equals Right side]
<=  [is relatively Less than or Equal]
<  [is relatively Less than]
 
  4 Cassette TAPE Commands (all begin with a Colon) no Printer??
:PRINT (optional Start,Size in Words) saves Words + CHECKSUM Byte
:INPUT (optional Starting address) loads saved Screen & Program
:RUN  [loads a Machine code into Screen top] then executes it
:LIST  [no arguments allowed, just read tape and check CheckSum]
 
  a REMark Command which goes anywhere in a Line but effectively ends it :
'.'  [aka 'Period' - useful for storing Bytes or half-Words from 0 to 255]
 
  and 2 spelled-out Commands :
CALL machine code  [preserve DE for RETurn]
STOP  [and return to Editor mode]
 
 
FUNCTIONs assign their value to be printed OR to a variable -
 
  18 Functions to Read Inputs :
=JX(1-4)  [Joystick X +/-position] - Horizontal
=JY(1-4)  [Joystick Y +/-position] - Vertical
=TR(1-4)  [TRigger status] - 0, or 1 when Pulled
=KN(1-4)  [KNob position] - 0 Right to 255 Left
=KP  [Key Press] - waits for an entry by the user
=&(0 to ??)  [from any InPort directly]
 
  3 Functions to Read Other values :
=PX(X,Y)  [Pixel] - 0 White, 1 Black
=SZ  [Size] - DFTLMT minus TXTUNF pointer
=ABS(+/-nnnnn) - ABSolute value of Word -32768 thru +32767
 
  and an enter 'WORD-shift' then '6' Function :
=RND(1 to +32767, or 0 un-ranged) - RaNDom number 0 to n-1
 
 
  Finally, some Special keys not part of the AstroBasic language :
'Halt' (stop sign) will Break into a running Program, whilst ...
'BLUE shift' at the same time as 'WORDs shift' causes Line Trace.
 
  to Edit an existing program while Not running, enter Line, press
'Pause' [once per old character/keyword, 'Delete' or add new text]
 
 
 
Have a Ball-y!
 
Flash Angstrom
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  \..  Richard Degler = fangs301@yahoo.com ::: (72 character guide) ==>
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