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Re: Apple //e hardware question

On 5/23/2013 8:06 AM, Bill Buckels wrote:

"Charlie"<charlieDOTd@verEYEzon.net>  wrote:


For instance, the //e doesn't use locations $C022, $C029 and $C034 for
registers/softswitches.  Are they safely available to use?


$C034 is in use and is not safely available for peripheral add-ons. The
Apple II device map is like latin.
$C034 is used for the border color and clock control bits on an Apple IIgs but I've never seen any information showing it used on a //e. Can you point me to some information showing what its used for? 


Accessing $C034 does click the speaker every other time, but would that be
a problem?


The Aztec C Sound function which I use in many of my programs plays music
using the speaker. Other programs do as well. Here is my code which has been
around since 1989...

<--- snip --->

TOPPER:;  /* loop the required note length */
#asm
         BIT $C030
#endasm
         j=pit;
COUNTER:;
         if(j--)goto COUNTER;
         if(temp--)goto TOPPER;

         /* wait for the duration specified by pitch */
         /* then click it again                      */

<--- snip --->
Yes, $C030 is the speaker on all Apple IIs, I believe. I assumed that $C034 clicks when accessed because the //e didn't fully decode the $C030 address. 

Charlie