2300 speed vs. 280 speed

[Ivan Drucker]

>So I've heard from several people that the 2300c is slower than the 
>280c, anyone know why this is? Being almost the same machine (the 2300 
>has the internal IDE drive which I always thought was faster) with the 
>faster processor, I'd have thought the 2300c was the faster Duo.

First, let's get one thing straight: When running a native PPC 
application which is not extremely disk-intensive, the 2300c is 
unquestionably faster than the 280c running the 68K version of the same 
application, as you would expect. No discussion.

However, disk-related functions, and the Finder itself, perform 
sluggishly. The reason is the lack of DR (dynamic recompilation) in the 
68K emulator, as is the case with all NuBus-based Macs (and PCI-based 
Macs running 7.5.2). A great deal of Mac OS 7/8/9 is 68K code, and all of 
it has to be emulated to run on the PPC chip. This is true for any 68K 
application, but also true for key chunks of the OS, such as the File 
Manager (!) and parts of the Finder itself, especially on older versions 
of the OS.

The lack of DR (as I understand it) in the emulator means that every 68K 
instruction has to be newly emulated, whereas DR provides signifcant 
performance gains by reusing PPC code generated for already-executed 
instructions. Or something like that. The point is that DR makes 
emulation way faster.

Fortunately, there is a really good solution to this problem, in the form 
of Connectix Speed Doubler, which replaces Apple's 68K emulator with a 
new one that uses DR. If you are using ANY PowerPC NuBus Mac with 
adequate memory, including the 2300c, you MUST run it. It's well worth 
the meg of RAM it occupies. It's been a long time since I've used it, so 
I can't remind myself of how much better it makes things, but my memory 
is that the difference is quite substantial, and enough to eliminate the 
seeming sluggishness of the 2300c. Speed Doubler also has some disk 
caching and file copying improvements for further speed benefit, but I 
never used them.

The bad news is that Speed Doubler is not compatible with Mac OS 9 
(though I think Mac OS 9 is inappropriate for the 2300c anyway due to its 
memory requirements). Also, it's no longer available, and even its 
product updates are no longer available, so I don't know how to tell you 
to (legally) get it. It seems to be available at amazon.co.uk though they 
will only ship to EU countries, as well as 
http://www.softjam.co.uk/acatalog/Boxed_Connectix.html, which doesn't say 
anything about restricted shipping. The latest version is 8.1.2, I think.

Ivan.