Sound

This program plays a single musical chord using the TS2068’s built-in SOUND command, then waits indefinitely for a keypress via PAUSE 0. The SOUND statement at line 10 configures the AY-3-8910 sound chip with seven register/value pairs in a single semicolon-separated call: register 7 sets the mixer (enabling tone and noise channels), registers 8–9 set channel volumes, registers 0–2 set the tone periods for the three channels, and register 3 sets a noise period. The REM at line 1 identifies it as a submission to RESET magazine’s 1986 Byte Power column, attributed to K. Boisvert. Line 2 is a blank REM or empty line used as a spacer in the listing.

Program Analysis

Program Structure

The program is minimal, consisting of just four lines. Line 1 is a REM comment crediting the author and publication. Line 2 is an empty or blank line acting as a visual separator. Line 10 issues the sound command, and line 20 halts execution until a key is pressed.

1. 10 SOUND ... — configures the AY-3-8910 sound chip and begins playback
2. 20 PAUSE 0 — holds the program open indefinitely after the sound fires

SOUND Register Breakdown

The SOUND keyword (TS2068 extension, displayed as } in zmakebas notation) allows multiple AY-3-8910 register/value pairs to be written in a single statement using semicolons. The seven pairs used here are:

Register 7 value 60 (binary 00111100) disables tone on channel C and enables noise on channel C while enabling tone on channels A and B, producing a two-tone chord blended with noise. No envelope registers (10–13) are set, so both active tone channels play at constant maximum volume.

Notable Techniques

• Packing all seven register writes into a single SOUND statement saves both tokens and execution time compared to seven separate calls.
• PAUSE 0 at line 20 is used here not as a keypress-wait idiom paired with INKEY$, but simply to prevent the program from terminating and silencing the AY chip immediately after the registers are set — the sound continues asynchronously.
• The omission of channel C tone period registers (4 and 5) is intentional; channel C is used for noise only as determined by register 7.

Bugs and Anomalies

Register 1 in the AY-3-8910 is the high byte of channel A’s tone period (only the lower 4 bits are significant). Setting it to 5 combined with register 0 value 10 gives a 12-bit period of 0x050A (1290 decimal), yielding a relatively low-pitched tone on channel A. Register 3 is the noise period register, not the channel B tone high byte — channel B’s high byte (register 3 is actually the noise period; channel B high byte is register 3 in AY numbering… wait: AY registers: R0=ChA fine, R1=ChA coarse, R2=ChB fine, R3=ChB coarse, R4=ChC fine, R5=ChC coarse, R6=Noise, R7=Mixer). Re-examining: register 3 is in fact the coarse (high) byte of channel B’s tone period, not the noise period — the noise period is register 6, which is not set here. This means the noise generator runs at its default/residual register value, and the program produces two tones (A and B) with noise potentially audible depending on the chip’s reset state.

    1 REM RESET 1986 BYTE POWER                WRITTEN BY K. BOISVERT
    2 
   10 SOUND 7,60;8,15;9,15;0,10;1,5;2,11;3,5
   20 PAUSE 0