which i/o ports are used for sound?

[nitrofurano]

On msx, i use a code like this for having some sound:

out $a0,7  ';- register 7: channel switch (OpenMSX warning: bit 6 should be 0)
out $a1,%10111110  ';- value
out $a0,0  ';- register 0: channel a frequency (16 bit, unsure if it is more or less significant byte)
out $a1,93 ';- value
out $a0,1  ';- register 1: channel a frequency (16 bit, unsure if it is more or less significant byte)
out $a1,4  ';- value
out $a0,8  ';- register 8: volume - channel a
out $a1,7  ';- value

There, the port $A0 is used for the psg register choosing, and $A1 for setting values.

 

The confusion is when i try to find which ports are used on Colecovision, which http://www.colecoboxart.com/faq/FAQ05.htm says it is from $C0 to $DF, and http://adamcon.org/pipermail/coladam/2012q3/002088.html from $E0 to $FF - which one is correct, and which are for setting register, and which are for outputting values?

Edited June 29, 2014 by nitrofurano

[CrazyBoss]

I just use FF.

 

But the MSX chip is not compatible with the Colecovision one. So you cant just change the port number you need to do som conversion.

[nitrofurano]

I just use FF.

 

But the MSX chip is not compatible with the Colecovision one. So you cant just change the port number you need to do som conversion.

 

thanks

 

btw, the documentation at http://www.smspower.org/Development/SN76489 looks quite confusing - how simple is to convert code that use ay-3-8910 to sn76489 and back? and where from can we find documentation comparing these both side by side?

Edited June 30, 2014 by nitrofurano

[nitrofurano]

and it seems that sn76489 misses some ay-3-8910 features like envelopes? (and we only can have some idea of envelopes simulating it controlling the volume during the sound play?)

[nitrofurano]

i'm trying this now ( copied from http://www.smspower.org/Development/SN76489 ) :

 

 

  ld a,%10001110
  out ($FF),a
  ld a,%00001111
  out ($FF),a
 
  ld a,%11011111
  out ($FF),a
 
  ld a,%11011111
  out ($FF),a
  ld a,%00000000
  out ($FF),a
 
  ld a,%11100101
  out ($FF),a
 
  ld a,%11100101
  out ($FF),a
  ld a,%00000100
  out ($FF),a

 

and getting no sound at all... :S - where from should we try examples that works?

[nitrofurano]

another thing i'm seeing is that you can play on ay-3-8910 2 octaves lower than sn76489 lower frequency limit? (A0 on ay-3-8910, and A2 at sn76489 - due on 12 bits for ay-3-8910 and 10 bits for sn76489, for 111861/hz value ) - from http://www.seventhstring.com/resources/notefrequencies.html i'm seeing that we can’t play most of the bass/cello notes scale...

Edited July 3, 2014 by nitrofurano

[+nanochess]

i'm trying this now ( copied from http://www.smspower.org/Development/SN76489 ) :

 

and getting no sound at all... :S - where from should we try examples that works?

This code will work. Read more carefully the documentation

 

ld a,$8a    ; Select channel 0, update lower 4 bits (contained in bits 3-0)
out ($ff),a
ld a,$0a    ; Continue updating channel 0, update higher 6 bits (contained in bits 5-0)
out ($ff),a
ld a,$9f    ; Select volume 0 (bit 7= 1=select), lower 4 bits are volume
out ($ff),a

[nitrofurano]

This code will work. Read more carefully the documentation

 

ld a,$8a    ; Select channel 0, update lower 4 bits (contained in bits 3-0)
out ($ff),a
ld a,$0a    ; Continue updating channel 0, update higher 6 bits (contained in bits 5-0)
out ($ff),a
ld a,$9f    ; Select volume 0 (bit 7= 1=select), lower 4 bits are volume
out ($ff),a

 

thanks! recently my doubt was that i didn’t know if %1xxxxxxx and %0xxxxxxx values should have some special sequence

[+nanochess]

 

thanks! recently my doubt was that i didnt know if %1xxxxxxx and %0xxxxxxx values should have some special sequence

Yep, technically a %00xxxxxx just after a %1rr0xxxx for register selection. (0/1/2)

 

Only for frequency registers.

 

And there are the four volume registers %1rr1xxxx and the control register %1110xxxx for noise channel.