[vcf-midatlantic] Original Macintosh Architecture Questions

David Riley fraveydank at gmail.com
Fri Jun 25 02:38:15 UTC 2021


On Jun 24, 2021, at 10:31 PM, David Riley <fraveydank at gmail.com> wrote:
> 
> On Jun 24, 2021, at 4:05 PM, John Heritage <john.heritage at gmail.com> wrote:
>> Last question on the Mac Audio --
>> 
>> Is it fair to say that if you wanted audio on the Mac, you basically wanted to digitally sample a sound/take a sound sample and then have the CPU shape it so it would output correctly?  (i.e. costing some CPU cycles)     
> 
> You could say that, but it would probably be more accurate to say that when the Mac came around, not many other machines had real sampled audio out, so the sound quality was pretty good for the time already.  But it wasn't perfect, as related in this excellent story from Andy Hertzfeld's recollections of the development of the original Mac: https://www.folklore.org/StoryView.py?project=Macintosh&story=Boot_Beep.txt
> 
> In any case, any application with high quality audio for the time (here I'm thinking something like Dark Castle, which actually has really great sound effects) probably either just lived with the iffy quality or pre-equalized the audio, but given that Dark Castle sounds pretty similar on a machine with a real sound chip like something from the II series, I doubt it makes that much of a difference. Keep in mind that a PWM through a properly tuned RC filter isn't going to sound a whole lot different from an actual DAC (again, delta-sigma DACs work basically on this principle, just a whole lot faster).
> 
> That site, by the way, is replete with stories you won't find anywhere else (aside from Andy's book, which is the contents of the site plus a few more stories and lots of pictures).  I really loved reading through it.

Also, speaking of, this is another great story from the same source about the development of the sound capabilities on the original Mac, including some details about the audio fetch during horizontal blanking: https://www.folklore.org/StoryView.py?project=Macintosh&story=Sound_By_Monday.txt


- Dave


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