SOUND driver
============
Note: 0-119, ten octaves from C0-B9
Channel: 0-2
Volume: 0-15
Noise: 0,1, off/on, ch. 2 only (SN limitation we impose on others,too)
Implementation: three channels is the lowest common denominator of SN, AY,
SID, and Pokey. Leaves channel 4 on Pokey free for timer.
For SID, use pulse with 50/50 duty cycle to get a clear tone.
All others play clear tone. Pokey might use distortion C
for low notes? Notes outside the playable range are either
transposed up/down, or ignored. Setting noise switches to
one of the LFSR noise types.
SOUND_VERSION
Enter:
Exit: A = API version
SOUND_BELL
Enter:
Exit:
SOUND_PLAY_NOTE
Enter: A = Note, X = Channel
Exit:
SOUND_SET_VOLUME
Enter: A = Volume, X = Channel
Exit:
SOUND_SET_NOISE
Enter: A = 0,1, X = Channel
Exit:
SOUND_SET_IGNORE_INVALID
Enter: A = 0,1
Exit:
TIMER driver
============
Granularity of time? Hertz might be computational expensive for platforms
that do not specifically have a timer frequency that can be set in hertz.
Perhaps a list of predefined values?
1Hz, 2Hz, 10Hz, 25Hz, 30Hz, 50Hz, 60Hz, 100Hz, 1000Hz, 15.7kHz (scan line)
Or maybe only one fixed frequency of 1 VBlank?
Commodore PET can only do VB on pin CB1 of its PIA?
Implementation: Oric, C64, BBC, VIC-20: CIA or VIA timer
Atari: Pokey timer or Antic (GPU) VBI
PET: PIA vertical retrace
Apple: No timers? Not even VB? Only IIc seems to have VBI
TIMER_VERSION
Enter:
Exit: A = API major version, X = API minor version
TIMER_GET_CPU_SPEED (API 1)
Enter:
Exit: YXA = 24-bit frequency in Hertz
Could be used for busy waiting timing loops if there's no timer
capability. Of limitted use on systems with cycle stealing (RAM
refresh, display memory access)
TIMER_WAIT_VBLANK (API 2)
Enter: X = Number of times (1-255, 0 is a nop)
Exit:
TIMER_GET_FRAME_RATE (API 2)
Enter:
Exit: A = 50 or 60
TIMER_SET_FREQUENCY (API 3)
Enter: XA = Frequency (?)
Exit:
TIMER_SET_CALLBACK (API 3)
Enter: XA = Address
TIMER_START (API 3)
Enter:
Exit:
TIMER_STOP (API 3)
Enter:
Exit:
JOYSTICK
========
JOYSTICK_VERSION
Enter:
Exit: A = API version
JOYSTICK_GET_STATUS
Enter: A = 0, 1 (joystick 0 or 1)
Exit: A = 0-7,8 (UP, UPRIGHT, RIGHT, etc... clockwise, 8 = center)
X = trigger
Brain dump below:
Thoughts? :smile: