RND

RND is a generative music program that drives multiple SOUND channels simultaneously using random parameter values drawn from DATA statements. Each iteration reads 20 random values covering channel registers for tone, volume, and envelope settings, with three PAUSE statements introducing variable timing between bursts of sound. The program loops 1,000 times (tracked by variable `a`) before silencing via a final SOUND command. A RESTORE at line 145 resets the DATA pointer back to line 160 each cycle, ensuring the RND expressions are re-evaluated on every pass.

Program Analysis

Program Structure

The program is organized into three functional phases: initialization (line 5), a main performance loop (lines 10–150), and a termination handler (line 155). The loop counter variable a is incremented at line 12 and tested at line 20; after 1,000 iterations the program branches to line 155, which silences three channels and halts. A RESTORE 160 at line 145 rewinds the DATA pointer before each GO TO 10, so the 20 DATA lines are re-read from the top on every cycle.

DATA and RND Evaluation

Lines 160–350 hold exactly 20 DATA items, each expressed as a parenthesized RND expression. Because BASIC evaluates expressions in DATA statements at READ time rather than at parse time, every READ call produces a freshly randomized value. The ranges are chosen to match the legal parameter widths of the SOUND command registers:

• Channel/register selectors: RND*63 and RND*31 (6-bit / 5-bit fields)
• Tone/frequency values: RND*255 (8-bit)
• Volume/envelope: RND*15 (4-bit)
• PAUSE durations: RND*100 (arbitrary centisecond range)

Timing Control

Three PAUSE statements at lines 80, 100, and 120 use the values read into variables O, P, and Q respectively, each ranging from 0 to 99 centiseconds. This introduces irregular, unpredictable gaps between successive SOUND bursts, contributing to the generative, non-repeating character of the output.

Notable Techniques

• RESTORE loop: Using RESTORE 160 rather than RESTORE alone pins the DATA pointer to a specific line, which is robust against any future DATA additions above line 160.
• Counter-driven termination: Rather than running indefinitely, the loop counts to 1,000 via variable a, giving the piece a defined length.
• Graceful shutdown: Line 155 explicitly zeros the amplitude on channels 8, 9, and 10 (SOUND 8,0;9,0;10,0) to silence the hardware cleanly on exit.

    5 LET a=0
   10 READ A,B,C,D
   12 LET a=a+1
   20 IF a=1000 THEN GO TO 155
   30 READ E,F,G,H,I
   40 READ J,K,L,M,N
   50 READ O,P,Q,R,S,T
   60 SOUND 7,A;6,B
   70 SOUND 0,C;1,D;8,E
   80 PAUSE O
   90 SOUND 2,F;3,G;9,H
  100 PAUSE P
  110 SOUND 4,I;5,J;10,K
  120 PAUSE Q
  130 SOUND 11,L;12,M;13,N
  140 SOUND 8,R;9,S;10,T
  145 RESTORE 160
  150 GO TO 10
  155 SOUND 8,0;9,0;10,0
  160 DATA (RND*63)
  170 DATA (RND*31)
  180 DATA (RND*255)
  190 DATA (RND*15)
  200 DATA (RND*31)
  210 DATA (RND*255)
  220 DATA (RND*15)
  230 DATA (RND*31)
  240 DATA (RND*255)
  250 DATA (RND*15)
  260 DATA (RND*31)
  270 DATA (RND*255)
  280 DATA (RND*255)
  290 DATA (RND*15)
  300 DATA (RND*100)
  310 DATA (RND*100)
  320 DATA (RND*100)
  330 DATA (RND*31)
  340 DATA (RND*31)
  350 DATA (RND*31)