#147 Emulate 3 ch. 4 or 8-bit D/A sound converter interface (MHB8255a chip)

[Arki55]

I've implemented 3 channel 4 or 8 bit D/A converter sound interface.

Implement emulation of 3 channel 8-bit D/A conversion interface based on the i8255A/MHB8255A chip. Supporting 4 or 8-bit through a dropdown setting in sound config.

Options:
- 4 bit / 8 bit mode (Standard should be 8 bit mode. Samples that use only 4 bits will be boosted when used in 4 bit mode, while 8 bit samples will be only static when played in 4 bit mode)
- Force OUT mode (some apps set wrong i8255 mode / conflict with BETA drive)
- If the sound feels a bit distorted, try lowering the volume in sound preferences
- It uses SOUND_STEREO_AY_NONE setting option to avoid crashing when in mono mode. Sound.c file needs some refactoring.

Used (mostly AFAIK) by
+ Sample Tracker (v. 2.0, 2.1, 3T, 3D).
+ Amiga Sound Emulator (ASE) - See https://cygnus.speccy.cz/popis_da_pro_ase.php

Sample Tracker has 4 songs on its disk/casette. Hard to find any other.
It is easier to find songs for ASE, as it emulates MODs from Amiga.

I used to own one back in the days, built it according to plans from FIFO or similar magazine.
Sadly it got dumped along with all my Didaktik stuff few years back..

Branches:

LIB: https://sourceforge.net/u/arki55/libspectrum/ci/arki55/features/T2-DAC-interface/~/tree/
APP: https://sourceforge.net/u/arki55/fuse/ci/arki55/features/T2-DAC-interface-app/~/tree/

[Arki55]

Pull requests:

LIB:
https://sourceforge.net/p/fuse-emulator/libspectrum/merge-requests/7/

APP:
https://sourceforge.net/p/fuse-emulator/fuse/merge-requests/11/

[Arki55]

See also

https://sourceforge.net/p/arki55-fuse-mod/tickets/2/