Editing Bally Astrocade (section)

=== Language features ===
Astro BASIC supported the following keywords:{{r|AstroBASIC|p=108-114}}
* Commands: <code>LIST</code>, <code>RUN</code>, <code>STOP</code>, <code>TRACE</code>
* Statements: <code>PRINT</code>, <code>INPUT</code>
* Structure: <code>GOTO</code>, <code>GOSUB</code>, <code>RETURN</code>, <code>IF</code> (but no <code>THEN</code> and no <code>ELSE</code>), <code>FOR-TO-STEP/NEXT</code>
* Graphics: <code>BOX</code>, <code>CLEAR</code>, <code>LINE</code>
* Tape Commands: <code>:PRINT</code>, <code>:INPUT</code>, <code>:LIST</code>, <code>:RUN</code>
* Functions: <code>ABS()</code>, <code>CALL()</code>, <code>JX()</code> (specified joystick's horizontal position), <code>JY()</code> (joystick vertical position), <code>KN()</code> (knob status), <code>PX(X,Y)</code> (pixel on or off), <code>RND()</code>, <code>TR()</code> (trigger status)
* Built-in variables
** (read only): <code>KP</code> (key press), <code>RM</code> (remainder of last division), <code>SZ</code> (memory size), <code>XY</code> (last LINE position)
** (write only): <code>SM=</code> (scroll mode), <code>TV=</code> (display ASCII character)
** (read/write): <code>BC</code> (background color), <code>CX</code> <code>CY</code> (cursor position), <code>FC</code> (foreground color), <code>NT</code> (note time),
* Math: + - × ÷
* Relational operators: < > = <= >= # [not equal] [the language did not support <>]
* Logical operators: × [AND] + [OR]

A period <code>.</code> at the start of the line was equivalent to <code>REM</code> in other BASIC implementations. Certain commands were handled by the keypad instead of by keywords: the RESET button was equivalent to <code>NEW</code> in other interpreters.

The language supported 26 integer variables <code>A</code> to <code>Z</code>, and two pre-defined [[array (data type)|arrays]], <code>@()</code> - which was stored starting after the program, ascending - and <code>*()</code> - which was stored from the top of memory, descending. The language lacked a <code>DIM</code> statement for dimensioning the arrays, the size of which was determined by available memory (<code>SZ</code>) not used by the program listing (2 bytes per item). Ports were accessed via the array <code>&()</code>, and memory was accessed via the array <code>%()</code>, rather than using [[PEEK and POKE]]. While the language lacked strings, <code>KP</code> would provide the [[ASCII]] value of a key press, which could be output to <code>TV</code>, meaning that characters could be read in from the keyboard, stored in an array, and then output.

The character display was 11 lines of 26 characters across. The resolution for the graphic commands is 88x160, with X ranging from -80 to 79 and Y ranging from -44 to 43.

Music could be produced in four ways:{{r|AstroBASIC|p=40,114}}
# The <code>PRINT</code> command, as a side effect, produced a unique tone for each character or keyword displayed.
# The <code>MU</code> variable converted numbers into notes.
# Ports 16 through 23 accessed a music synthesizer.
# The sound-synthesizer variables <code>MO</code> (master oscillator), <code>NM</code> (Noise Mode), <code>NV</code> (Noise Volume), <code>TA</code> (Tone A), <code>TB</code> (Tone B), <code>TC</code> (Tone C), <code>VA</code> (Voice A volume), <code>VB</code> (Voice B volume), <code>VC</code> (Voice C volume), <code>VF</code> (Vibrato Frequency), <code>VR</code> (VibRato). (Added to Astro BASIC but not in Bally BASIC.)