Re: Programming the DOC pt2

[irsman@iastate.edu (Ian Schmidt)]

In article <mbusse.0tc5@amiganet.chi.il.us> mbusse@amiganet.chi.il.us (Marco Busse) writes:
>
>        lda     SOUNDCTL
>        and     #$F0
>        ora     #$0x
>        sta     SOUNDCTL

SoundCtl is a write-only register, at least for the volume bits.  You must
read the system volume from E1/00CA (which is normally set to the Control
Panel volume).  This is why all sound software accesses the sound GLU with
a sequence like the following:

Busy      lda >SoundCtl
          bmi Busy           ; if DOC is busy, wait for it to synch up
          lda >$e100ca
          and #$0f
          ora #$x0
          sta >SoundCtl

-- 
        Ian Schmidt - Two Meg Software: irsman@{iastate.edu | aol.com}        
"I will choose a path that's     | Author of AudioZap, MODZap, and more.
 clear: I will choose free will" | Co-author of SoundConvert and DeskTracker.
 - N. Peart, 1980                | Presenting: the compressed Amiga check _/