[Coco] more 1 bit madness

[Richard E Crislip]

Hi Nick,

Isn't  a shame that Tandy chose not to put sound and video co-processors 
in the CoCo similar to the C-64 or Atari? That 6809 would have blown 
everything out of the water at the time.

On 01/20/2014 01:10 AM, Nick Marentes wrote:
> Allen Huffman <alsplace at ...> writes:
>
>> On Jan 19, 2014, at 5:41 PM, Steve <6809er at ...> wrote:
>>> I took look at the code that Simon just posted today and it could never
> be used while a game is running.  The CPU
>> overhead is just too much.
>>
>> Grumble. I was afraid that might be the case.
> Generating music "on the fly" eats into much of the CPU time required by a
> fast action type game on the CoCo.
>
> You can lower the sound quality to reduce the overhead but then it starts
> sounding very choppy and buzzy with heaps of aliasing.
>
> The best way to provide music within a fast action game is to use whole
> sampled sound. This has the overhead of requiring a lot more RAM and limits
> the length of a tune but it means the music routine is not spending time to
> generate the musical notes. It merely throws a byte out to the sound output
> port at a set interrupt interval. The frequencies and multiple sound
> channels have already been pre-processed.
>
> I use a 2 voice interrupt driven sound routine allowing for 2 sound effects
> to occur simultaneously, such as firing and explosions.
>
> No reason why I couldn't use one for sound effects and the other to play a
> sampled music track but most people will find the repetitive sound track
> monotonous.
>
> If you're a good programmer like John Kowalski, who can create the
> impossible, maybe a proper 2 channel MOD type player can be had with
> gameplay but I have always tried to keep my sound overheads low to allow for
> as much as possible to the game itself. (I'm also not as good as John).
>
> Nick
>
>
>
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