I'll try to explain Colecovision sound programming as best as I can. The three best resources I have found are:
1. "Colecovision Coding Guide" by Daniel Bienvenu starting at page 198. Good documentation on sound structure.
2. "Official Colecovision Programming Manual" section 7 Sound Generation
3. Disassembling Colecovision games that actually use OS7 calls, a lot of them do not.
Here are the equates I'll reference:
SOUND_INIT:EQU1FEEh;B=concurrent voices+effects, HL=song table
SOUND_MGR:EQU1FF4h
PLAY_IT: EQU1FF1h;B=Song number
PLAY_SONGS:EQU1F61h
TURN_OFF_SOUND:EQU1FD6h
NUM_SOUND_DATA_AREAS:EQU5
Generating sound on the Colecovision using OS7 requires 4 steps:
1. Initialization
2. Sound Definitions
3. VDP routines
4. Playing (starting) a sound
1. Initialization
; Initialize Sound
CALLTURN_OFF_SOUND
LDB,NUM_SOUND_DATA_AREAS;number of active voices+effects, minimum of 4 for 4 channel sound
LDHL,SOUND_TABLE;pointer to memory location where you will define your sounds to their data areas, see Sound Definitions below
CALLSOUND_INIT
2. Sound definitions.
You can have multiple sounds use the same data area. Playing a sound in the same data area will of course stop the sound that was previously playing. Each sound data area requires 10 bytes of RAM.
SOUND_TABLE:;the pointer used in initialization
;pointer to sound data,ram sound/channel data area
DW DATA_SOUND_01H,72E0h ; click sound
DW DATA_SOUND_02H,72EAh ; music channel 1
DW DATA_SOUND_03H,72F4h ; music channel 2
DW DATA_SOUND_04H,72FEh ; music channel 3
DW DATA_SOUND_05H,7308h ; music channel 4
DW 0,0;table must end with this
DATA_SOUND_01H:
DB 03H,00H,66H,04H,00H,00H,75H,11H
DB 10H;sound stops after one play, no repeat
You would have one of these for each sound as defined in your SOUND_TABLE. So for this example I would need DATA_SOUND_02H, DATA_SOUND_03H, DATA_SOUND_04H and DATA_SOUND_05H also.
3. VDP routine
During your VDP Interupt routing you must call two OS7 sound routines (PLAY_SONGS and SOUND_MGR) in a specific order to play your sounds/music and keep them playing.
Example VDP routine:
VDPINT:
;Save all registers
PUSHAF
PUSHBC
PUSHDE
PUSHHL
PUSHIX
PUSHIY
EXAF,AF'
PUSHAF
EXX
PUSHBC
PUSHDE
PUSHHL
;sound routines
CALLPLAY_SONGS
CALLSOUND_MGR
;Now restore everything
POPHL
POPDE
POPBC
EXX
POPAF
EXAF,AF'
POPIY
POPIX
POPHL
POPDE
POPBC
;
INA,(0BFh);Side effect allows another NMI to happen
;
POPAF
;
RETN
4. Playing (starting) a sound
In order to start a sound playing you would call the PLAY_IT OS7 routine. If you wanted to play a 4 channel song you would make 4 calls to PLAY_IT with each call starting one of the channels.
;example to play a simple sound
LDB,1;start sound 1
CALLPLAY_SOUND_IN_B;play sound in B register
;example to play a 4 channel song
LDB,2;start music channel 1
CALLPLAY_SOUND_IN_B;play sound in B register
LDB,3;start music channel 2
CALLPLAY_SOUND_IN_B;play sound in B register
LDB,4;start music channel 3
CALLPLAY_SOUND_IN_B;play sound in B register
LDB,5;start music channel 4
CALLPLAY_SOUND_IN_B;play sound in B register
;--------------------------------------------------------
;Input: B song to play
PLAY_SOUND_IN_B:
PUSH AF
PUSH BC
PUSH DE
PUSH HL
PUSH IX
PUSH IY
CALL PLAY_IT
POP IY
POP IX
POP HL
POP DE
POP BC
POP AF
RETStatistics: Posted by pearsoe — Wed Nov 20, 2019 6:27 pm
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