Path: utzoo!attcan!uunet!cs.utexas.edu!rutgers!apple!phil
From: phil@Apple.COM (Phil Ronzone)
Newsgroups: comp.sys.mac.programmer
Subject: Re: System 7.0 Q & A
Message-ID: <30935@apple.Apple.COM>
Date: 17 May 89 17:00:38 GMT
References: <30353@apple.Apple.COM> <4666@okstate.UUCP> <1787@internal.Apple.COM> <7266@hoptoad.uucp> <13472@dartvax.Dartmouth.EDU> <7321@hoptoad.uucp>
Organization: Apple Computer A/UX Group
Lines: 26

In article <7321@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes:

>And all of these low memory locations can be trapped by the MMU and handled
>transparently to the application.

Well, that is not economical. When we launched a version of Lode Runner
under A/UX, guess who was watching the clock ticks rather than using an
A-line trap? (A/UX normally updates the ticks much less frequently).

Nice thing about it was Lode Runner ran about 5x slower, so I could win.

You can now set an environment variable, and A/UX will issue signals to update
the clock ticks lowmem much faster -- except now that process is taking a lot
of signals.

Point is -- a lot of looking at the low memory globals CAN be caught, but
would (could) be very expensive in cycles.


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