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From: cross@spitfire.i.gajendra.net (Dan Cross)
Newsgroups: comp.os.linux.misc,alt.folklore.computers
Subject: Re: Unix on x86, Hmmm ... Downloaded Xenix - But It's *41* Floppies Worth
Date: Sat, 30 Aug 2025 12:19:06 -0000 (UTC)
Organization: PANIX Public Access Internet and UNIX, NYC
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In article <suScna_OAeil4C_1nZ2dnZfqnPSdnZ2d@giganews.com>,
c186282  <c186282@nnada.net> wrote:
>On 8/29/25 11:27 PM, Lawrence D’Oliveiro wrote:
>> On Fri, 29 Aug 2025 23:51:18 GMT, Charlie Gibbs wrote:
>> 
>>> But there definitely was a period before that where the button vanished
>>> (although there would have been motherboard pins if you wanted to dig
>>> into it).
>> 
>> Apple included a little springy clip thing (the “Programmers’s Switch”) in
>> the box with each of those original classic-form-factor Macintoshes. When
>> installed, pressing one side triggered NMI (used for invoking the resident
>> debugger), while the other side triggered the RESET line (hard reboot).
>> 
>> I still have the muscle memory: seated in front of the machine, reach
>> around with right hand, far side was NMI, near side was RESET.
>
>   Hmmm ... how did they implement that ? How did it
>   differ from just using the power switch ???

Presumably the NMI would enter a debugger.  RESET would yank the
CPU and peripheral reset lines.

>   In THEORY that kind of 'reset' SHOULD include at
>   least ATTEMPTS to shut down a few important daemons.
>   MOST important, the HDD cache ... DO try yer best
>   to write-out the cache before going off.

The original Macintosh had daemons, important or not.  For that
matter, it didn't ship with a hard disk drive, either.

>   "Reset" buttons are mostly good, but on the company
>   servers I always disconnected those, so no dink could
>   just accidentally bump into the switch while looking
>   for something else. REAL power switch, like a 3-sec
>   delay before anything happens.

Those weren't Macs.  :-)

        - Dan C.