Wow! Good articles and thanks David! Since you mentioned you loved the original hardware design of the Mac, I hope you won't mind a few more questions.. Interesting on the IWM making it to the Mac, I knew that was a really innovative chip on the Apple II, but didn't realize it also was used in early Macs. What was the reason the PC used 9 sectors per track while the Mac and Amiga used 10/11 sectors per track each on the 3.5" floppies? (I assume the ST defaulted to 9 sectors per track to stay compatible with DOS disks..) Was it because the PC technically predated the original Mac and Amiga/ST and the early drives/disks were risky with higher densities? Did Apple trade anything off for 400KB floppies in the Mac? Hardware wise, is it fair to say that the Mac probably cost less to manufacture in ~ 1985 than say the Amiga 1000 or Atari 520ST? The Amiga had several custom chips, and even the ST seemed to have more ICs on board, though monitors were optional for both. (I think in 1984 RAM was still very expensive so I can see why the 128KB Mac would be high, especially as an early adopter premium). I always assumed the Mac premium was due to it's software library and 'brand' (at least in the US) at the time, but curious if there were any hardware reasons for the cost. Last question -- were there 'fast ram' upgrades for the original Macs (say pre-1990) that would allow the 68000 access to local memory for faster execution than RAM on the shared bus? or did all RAM have to be shared? It looks like the ram size limitations on the early Macs were relatively close to what the 68000 could do.. Thanks! On Thu, Jun 24, 2021 at 10:38 PM David Riley <fraveydank@gmail.com> wrote:
On Jun 24, 2021, at 10:31 PM, David Riley <fraveydank@gmail.com> wrote:
On Jun 24, 2021, at 4:05 PM, John Heritage <john.heritage@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_Monda...
- Dave