Message-ID: <242@ssc-vax.UUCP>
Date: Wed, 5-Dec-84 13:17:54 EST
Article-I.D.: ssc-vax.242
Posted: Wed Dec  5 13:17:54 1984
Date-Received: Thu, 6-Dec-84 06:01:12 EST
Distribution: net
Organization: Boeing Aerospace Co., Seattle, WA
Lines: 43

>  In December issue of RUN magazine on page 164 is an article and
>  some listings of programs to play Christmas carols.  These are written
>  for the VIC-20.  What must I change to get these programs to run on
>  the C-64?

Your Computer :-).

Actually, one of the nice things about the VIC was the ease of making music.
The C-64 sounds better, but is more difficult to work with.  These are the
steps I would use:

1.  Go through the VIC program, and, using the table in the VIC manual,      
determine the note being played.

2.  Using the C-64 manual, determine the proper two pokes for the equivalent
note.

3.  Using the VIC program, replace the frequency values in the data statement
with the equivalent two pokes for the '64, changing, for example, the "READ A:
POKE 36874,A" type statements with, for example, "READ A:READ B:POKE 54272,A:
POKE 54273,B".

4.  Whereever a VIC voice is poked with a value less than 128 (i.e., turning off
that voice) turn off the C-64 voice by clearing the 0 bit in the voice select
location (54276, etc).  Whenever the voice starts up again, the proper waveform
must first be selected.

5.  At the start of the program, set values for the ASDR... try some sample
values, then adjust to taste.

6.  Of course, don't forget to set the master volume...

Simple as 3.14157, eh?  Now, instead of doing this, run out to your nearest
user group and beg a copy of the Christmas program Commodore was handing out
two years ago... good sound and graphics, if you don't mind a short Commodore
commercial at the end (...ONLY $595).

					    Ron Wanttaja
					    (ssc-vax!wanttaja)

"I can't say much about our profession, but         
 compared with respectibility, it is comparatively honest."