eacj@batcomputer.tn.cornell.edu (Julian Vrieslander) (03/10/87)
I have seen conflicting descriptions of the sound generator hardware in the
Mac II. The sampling rate has been mentioned as 44.1 kHz (same as CD's), into 2
channels, with 16-bit samples. Elsewhere, there was a report that the samples
were 8-bit (suggesting that a 16-bit word contains the samples for both channels
in a given sample period), and a claim that new synthesis modes were available
in the Mac II sound driver.
So what is the "best" available sampling rate and sample bitwidth per each
channel? Can a Mac II (without peripheral cards) output genuine 16-bit freeform
sound into each channel? That would allow some fairly impressive beeps. Can
anyone report distortion and noise specs? What type of post-conversion
filtering is used? Can the sampling rate be varied?
Perhaps this will all be revealed when Apple releases the new doco, but I'm an
impatient lad.
--
Julian Vrieslander, Neurobiology & Behavior, Cornell Univ., Ithaca, NY 14853
UUCP: {cmcl2,decvax,rochester,uw-beaver,ihnp4}!cornell!batcomputer!eacj
BITNET: eacj%tcgould.tn.cornell.edu@crnlcs.BITNET
ARPA: eacj@tcgould.tn.cornell.edu MA BELL: (607) 255-3594mark@apple.UUCP (03/10/87)
Here are some responses to some of the sound and music
questions for Macintosh SE & II floating around the net:
1) Old music and MIDI programs should run with no trouble
on the Macintosh SE. There has been no change in the
sound hardware for that machine and as far as other
things go, compatability is VERY high.
2) Macinotsh II has a new Apple Sound Chip (ASC). The ASC
has EITHER: stereo sample play back OR four voice wave
table synthesis in hardware (what you could do in software
on a machine with a 68020 is unclear, but I've heard
some developers remark that 16 voices would be very easy.)
For either mode all samples are 8 bit, and the sample rate
is either 44.1 kHz CD rate, or the old Macintosh rate,
22,254.5454 Hz. Note that the analog sections are exceptionally
clean and the stereo output jack will drive both line level
inputs (like your stereo) AND walkman-style headphones or
self-powered speakers (with the volume in a usable range).
-Mark Lentczner
ATG Graphics & Sound Group
Apple Computer, Inc.
20525 Bandley Drive, MS:22Y
Cupertino, CA 95014
mark@apple.CSNET
{dual,ios,voder,nsc}!apple!mark.UUCP
P.S.: The above information aught to be correct, I wrote the
Sound Manager in the Macintosh II rom and helped designed the
Apple Sound Chip. It was fun doing it, I hope you all have
fun using it and making it do great things!
--
-Mark Lentczner
ADG Sound Group
Apple Computer, Inc.
20525 Bandley Drive, MS:22Y
Cupertino, CA 95014
mark@apple.CSNET
{dual,ios,voder,nsc}!apple!mark.UUCP