Switching Mac Applications


Author: Kim Helliwell
Date: 15 Jan 1985 3:46 pm

This Saturday past, at the Apple 32 User's meeting, I saw a demo of a new
program for the Mac which should be of interest to all.  The demo was  
conducted by Andy Hertzfeld, who is writing the program for Apple.  It is
a "pseudo" desk accessory (pseudo, because it is not a DA, but it is accessed
thru a selection under the Apple menu . . .), which allows the user to set
up, say, a work session involving up to four Mac applications.  Once the  
applications are loaded, "Switcher" allows you to *INSTANTANEOUSLY* switch
between those applications.  The instantaneous switching is real--the time
it takes to scroll the screen of one application off horizontally while
scrolling the next application's screen on!  Or, if you prefer, the scrolling
animation can be suppressed, and the change accomplished with a flicker of the

What the program does is partition a 512K Mac's memory with a partition for
each application, and on a keystroke command does a "context switch" to the
application heap of the appropriate application.  Partition size is user
settable, with both preferred and minimum partition sizes.

For some uses, this is a much better use of the "extra" memory in a 512K mac
than a RamDisk, since only one copy of any application is in memory at a

About the only drawback I see is you apparently aren't allowed to have
multiple copies of a single application to switch between--say MacWrite
open on two different files, unless the two MacWrite's come from different
disks.  I guess that's a minor problem, however.

Hertzfeld plans to deliver the completed first release to Apple about the
first week in Feb.  He says it will be distributed to dealers probably early
March.  It will be FREE to Mac owners, but will not be considered "Public
Domain".  Presumably, the larger Mac user's groups will get copies and will
be allowed to distribute them, however.

Switching Mac Applications
115 Jan 1985 3:46 pmKim Helliwell