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Hi everyone,
Apple's ROM crew has done it again: I own a Centris 650. The other day, I
powered up my Mac, and decided that I should immediatley turn off my Mac so
the DAT drive could power up first. Instead of just turning the power off,
I hit the interrupt button. I heard this interesting =-D tune come from my
Mac. I'm not sure, but I think it's a hidden ROM thing that patches the
interrupt key. In the past, I've heard that Quadra 840av's exhibit a wierd
quality like this too when the power key is held down... except it drops
you into a monitor type thing instead of a tune. Here are steps to reprodue
this:
1) Hit the Power Key on the keyboard. (I dont think it matters, as long as
your Mac is _off_ initially. It would be cool if someone or I could figure
out a way to make it do this on every restart.
2) Listen for the "Bzzzzzzzzt" of the power supply getting power.
3) While listening, within 2 seconds of turning it on, hit the interrupt key.
4) Enjoy the short tune it plays.
I checked; pressing some keys on the keyboard does not make the Mac act
like a MIDI keyboard based on which key was pressed.
For the rest ofyou who might not have a chance to hear the tune, I tape recorded and then
digitized what the C650 plays. 22KHz so that you can analyze it if you
like--sorry about the background noise. In the C650 ROM also is a "Brass
Horn" beep. It sounds like a little horn that squeaks on a kid's bike. I
wont include that, probably because of pattent/copyright violations.
(Hint: Use ROMmie to get your Mac's ROM resource and look for sounds using
ResEdit. I believe it's on info-mac in /dev.)
One thing I would like to pose is this: could something, even more special,
happen if the music's note-representation were typed in? =-D
Questions, comments, anything else? Email me.
Enjoy!
--Steve
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quadra-700-clock-mod-145.txt
Text file for tech folder which describes technique for changing Quadra
700 clock speed. This version includes cooling fan installation, custom
speed oscillators, thermal data, caveats regarding socket pins, and
performance data. At the time of posting, the author has reports of 33
Q700's modified in this way. Some have been running this way for months
without additional cooling. Three machines required cooling for
accelerated operation.
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This procedure should only be attempted by users experienced in circuit
board fabrication and repair. You must desolder a component on a
multi-layer motherboard. Such boards are fragile and expensive to
repair. This is NOT a good first soldering project. The process
voids your warranty. If you are not dissuaded by the above, read on