Instructions
Move the joystick (cursor keys) around the grid to select tone (vertical axis) and frequency (horiziontal axis, values 0…31). Press the button (space bar) to play.
Use Select and Reset switches (F11, F12) to adjust the audio volume.
(Keyboard settings in the emulator may differ for locally saved presets. You may reset these by the “Help & Settings” menu [Controllers / Defaults] available by the gears icon at the bottom right corner of the emulation. You may emulate a steady rhythm by the turbo fire trigger, normally mapped to DEL, and adjust the BPM by its repeat frequency in the “Quick Options”.)
About
This is a tiny test application I wrote to explore sound on the Atari VCS / Atari 2600. The information provided by the Stella Programmer's Guide is a bit scarce:TIA Registers AUDC0, AUDC1
| Hex | D3 | D2 | D1 | D0 | Type of noise or division |
|---|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 | set to 1 |
| 1 | 0 | 0 | 0 | 1 | 4 bit poly |
| 2 | 0 | 0 | 1 | 0 | div 15 -> 4 bit poly |
| 3 | 0 | 0 | 1 | 1 | 5 bit poly -> 4 bit poly |
| 4 | 0 | 1 | 0 | 0 | div 2 : pure tone |
| 5 | 0 | 1 | 0 | 1 | div 2 : pure tone |
| 6 | 0 | 1 | 1 | 0 | div 31 : pure tone |
| 7 | 0 | 1 | 1 | 1 | 5 bit poly -> div 2 |
| 8 | 1 | 0 | 0 | 0 | 9 bit poly (white noise) |
| 9 | 1 | 0 | 0 | 1 | 5 bit poly |
| A | 1 | 0 | 1 | 0 | div 31 : pure tone |
| B | 1 | 0 | 1 | 1 | set last 4 bits to 1 |
| C | 1 | 1 | 0 | 0 | div 6 : pure tone |
| D | 1 | 1 | 0 | 1 | div 6 : pure tone |
| E | 1 | 1 | 1 | 0 | div 93 : pure tone |
| F | 1 | 1 | 1 | 1 | 5 bit poly div 6 |
So, here they are: All the sounds there are on the VCS, united on a funky screen, ready to be explored. Please mind that the frequences result from divisions of a base frequency and are not exactly chromatic tones. Moreover, some "sounds" (0, “set to 1”, and B, “set last 4 bits to 1”) are apparently just providing internal functionality and do not produce an audible noise or tone.
Downloads
Atari 2600 game ROM image files (4K):
- Studio2600.bin (NTSC)
- Studio2600_PAL60.bin (PAL 60Hz)
The application (cartridge) has been developed as part of my project for RetroChallenge 2018/04.
This web pages uses an embedded version of the Javatari emulator by Paolo A. Peccin to run the NTSC version of "Studio2600" (by N. Landsteiner, 2018).