1.) Square Wave
The TED is the defining chip of the Commodore Plus/4 series of 8-bit home computers. It handles graphics, 2 joysticks, part of keyboard input, timing, and sound.
The exact meaning of TED varies with sources:
- "Text Editing Device" (Wikipedia since October 2004)
- "Text Editor" (C= Hacking, Issue #12, March 1996)
- "the 7360 TExt Display chip" (note the uppercase E; 264 Hardware Specification, chapter 4, December 1983)
On each of 2 voices, you can choose a pitch in 1024 steps. Compared to the VIC, high notes are in tune, but the bass does not get below A2 (110 Hz). Low noise actually sounds like noise, although you may notice a pattern as it gets higher.
For all 2 voices together, you can only choose one volume, from 0 to 8. Changing this volume, while either voice is on, produces a click; the greater the change, the louder. This allows to play unsigned PCM samples on a 3rd voice.
The original 7360 was still being produced in January 1984.
The more common cost-reduced 8360 chip was already being produced in July 1984.
Many Commodore 16 and Plus/4 games play music and sound effects on the TED.
VICE and YAPE emulate the Plus/4 series. YAPE has been in development for longer and has shown more compatibility than VICE, except that YAPE 1.2.0 is very slightly too fast.
- zimmers.net/anonftp/pub/cbm/plus4/programming/manual/manual.html - Commodore's 264 Hardware Specification and datasheet.
- en.wikipedia.org/wiki/MOS_Technology_TED - Wikipedia.