October 28, 2001
Classic is the application that allows you to
run older Mac OS applications that cannot run directly under
Mac OS X. In this it is similar to Virtual PC. The Classic
layer within OS X, sets up an environment in which Mac OS
9.x can run. When you click on an application that will not
run in OS X, the Classic layer responds by launching Mac OS
9.x. You will see Mac OS 9.x go through the boot process and
once that is done you will have the two OS's running at the
same time. Bring a Classic application to the forefront and
you'll be presented with the classic Mac OS interface. Bring
a OS X application to the front and you are once again dealing
with the new operating system's look, feel and technology.
Applications within the Classic environment cannot take advantage
of the advanced technologies of Mac OS X, such as preemptive
multitasking, or symmetric multiprocessing. Nor can they
utilize the increased stability of Mac OS X.
Below we compare performance when booted under
Mac OS 9.2.1 and when booted under Mac OS 10.1 but running
applications in the Classic environment using the same Mac
OS 9.2.1. Apple has done a great job of both making the experience
of moving between Mac OS X and Classic Mac OS almost seamless,
and in keeping the performance of the Classic layer very good
- as you'll see from the benchmark results below.
All test were run on a dual processor G4/800
tower with 768 MB of RAM. Higher scores are better.
This test copies a single folder with several
This test copies a single large graphics
This Quake test is more processor intensive.
The Classic application keeps up remarkably well
Here the Quake test is almost exclusively
dependent on the the graphics card
This test stress both the processor and graphics
AltiVec is what Apple refers to as the 'Velocity
Engine' of the G4 processor
Booting and Rebooting is very fast in Classic