The Mac Plus came with an 8 MHz 68000 CPU; the Brainstorm upgrade replaces that with a low power 16 MHz 68000. Brainstorm had the guts to claim it could more than double performance. Some claims just beg to be tested.

I had the Brainstorm upgrade installed in my Mac Plus about nine years ago, sold the system a few years later, and recently reacquired it. (See My Mac Plus for all the details.) After all these years, I could finally test Brainstorm’s claims.

The only software I could no longer run after having the Brainstorm accelerator installed was Dark Castle, which runs from a floppy disk with its own system software.

At that time, my hard drive was a 40 MB Quantum, and I was able to run it with a 1:1 interleave with the Brainstorm accelerator and SCSI Accelerator.

The hard drive is a 160 MB Quantum, the same one I used when benchmarking a regular Mac Plus. Both computers have 4 MB of memory and were tested with the same System 7.5.5 configuration.

Remember that benchmarks are arbitrary. They measure certain types of performance that may or may not reflect the way you work.

Speedometer 3.06

The system was tested on 2000.10.08 using System 7.5.5. Results are relative to a Mac Classic, which rates 1.0. Numbers are rounded off to two decimal places.

The first set of numbers compares performance at different disk cache settings.

Stock 8 MHz Plus
cache     CPU   graphics  disk    math
 32 KB    0.87    0.91    0.67    0.99
 64 KB    0.87    0.91    0.67    0.99
128 KB    0.87    0.91    0.67    0.99
256 KB    0.87    0.91    0.57    0.99
         
Plus with 16 MHz Brainstorm
cache     CPU   graphics  disk    math
 32 KB    2.02    1.96    1.27    2.18
 64 KB    2.03    1.96    1.27    2.18
128 KB    2.03    1.96    1.27    2.18
256 KB    2.03    1.96    1.15    2.18
         
Brainstorm Performance vs. Stock
cache     CPU   graphics  disk    math
 32 KB    233%    215%    188%    220%
 64 KB    233%    214%    189%    220%
128 KB    233%    214%    189%    220%
256 KB    233%    214%    203%    220%

The cache setting should have little influence on non-disk tests, which these numbers bear out. With this particular setup, cache size makes no appreciable difference except at 256 KB, where it actually reduces performance on both the stock Plus and the accelerated one – although is slows the faster Plus less.

These benchmarks bear out Brainstorm’s claims: The upgrade makes the Mac Plus over twice as fast. It even improves SCSI throughput.

Having just completed benchmarks on the stock Plus and the Brainstorm upgraded one, I can also say there’s a huge subjective difference between the two. The basic Plus just feels slow and tired; the Brainstorm makes it a much perkier machine and a far better System 7 performer.

Is a Mac Plus with a Brainstorm accelerator as fast as a 16 MHz 68030-based SE/30? Not hardly. The SE/30 scores over twice as high on the CPU test, nearly twice as high on the graphics and disk tests (using the same hard drive), and about triple on the math tests.

Still, nine years ago I thought Brainstorm was an excellent value for $200. Today, I wouldn’t want to run a Plus without it.

Speedometer 4.02

Speedometer 4 and later benchmarks don’t run on 68000-based Macs.

Keywords: #macplus #brainstormupgrade

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