furnace/doc/7-systems/zxbeep.md

# ZX Spectrum beeper

rather than having a dedicated sound synthesizer, early ZX Spectrum models had one piezo beeper, controlled by Z80 CPU and ULA chip. its capabilities should be on par with an IBM PC speaker... right?

not really - very soon talented programmers found out ways to output much more than one square wave channel. a lot of ZX beeper routines do exist, but as of 0.6 Furnace supports only a Follin/SFX-like engine with 6 channels of narrow pulse wave and click drums.

# effects

- **`12xx`**: set pulse width.
- **`17xx`**: trigger overlay drum.
  - `xx` is the sample number.
  - overlay drums are 1-bit and always play at 55930Hz (NTSC) or 55420Hz (PAL).
  - the maximum length is 2048!
lots of doc updates 2022-10-16 05:53:05 +00:00			`# ZX Spectrum beeper`
docs update (#519) * docs update mentions of fractal, new chips documentation, and other minor stuff * add a link to the Fractal repo as suggested by @breakthetargets * better wording, less typos 2022-06-06 14:49:39 +00:00
lots of doc updates 2022-10-16 05:53:05 +00:00			`rather than having a dedicated sound synthesizer, early ZX Spectrum models had one piezo beeper, controlled by Z80 CPU and ULA chip. its capabilities should be on par with an IBM PC speaker... right?`
docs update (#519) * docs update mentions of fractal, new chips documentation, and other minor stuff * add a link to the Fractal repo as suggested by @breakthetargets * better wording, less typos 2022-06-06 14:49:39 +00:00
lots of doc updates 2022-10-16 05:53:05 +00:00			`not really - very soon talented programmers found out ways to output much more than one square wave channel. a lot of ZX beeper routines do exist, but as of 0.6 Furnace supports only a Follin/SFX-like engine with 6 channels of narrow pulse wave and click drums.`
docs update (#519) * docs update mentions of fractal, new chips documentation, and other minor stuff * add a link to the Fractal repo as suggested by @breakthetargets * better wording, less typos 2022-06-06 14:49:39 +00:00
			`# effects`

Fixing something I botched. Hey, all those files I thought I clobbered! 2023-06-24 01:13:37 +00:00			- `12xx`: set pulse width.
			- `17xx`: trigger overlay drum.
fix documentation regarding ZX beeper samples 2022-08-16 03:44:55 +00:00			- `xx` is the sample number.
			`- overlay drums are 1-bit and always play at 55930Hz (NTSC) or 55420Hz (PAL).`
lots of doc updates 2022-10-16 05:53:05 +00:00			`- the maximum length is 2048!`