Posted By
JamesD
on 2013-08-05
13:17:07
|  Re: Z80 GUI: SymbOS
Apple II a closed system? Say what? It was documented inside and out even down to the hardware logic. The first Apple II came with schematics and even some assembly listings.
Did you try to download a manual for any DOS listed on those pages?
The numbers will vary by DOS version for one thing.
If you can't find numbers anywhere, you can take another approach.
What is the rotation speed of the disk?
How many sectors are on a track and how much does a sector hold?
Do some math and you'll have an estimate of the data transfer rate.
After transfer the CPU has to deal with the data. Look at the info on interleave and you should be able to figure out how long it takes to decode a sector. This will let you calculate throughput... which the articles pretty much stated was different for every DOS version so stick with what people actually use, DOS 3.3 or ProDOS.
The decoding is actually faster than that but it's a moot point since the DOS won't read anything before the start of next available sector after it's done decoding.
That will give you an estimate but it doesn't account for alternate DOS versions, DOS speedup patches, etc... and yes, those do exist but not everyone used them. Patches were listed in magazines, newsletters, etc...
Clearly, any floppy numbers you get are strictly worst case with standard DOS and you are comparing VS fast loaders on the +4. Hardly a fair comparison.
Consider this...
Apples weren't all 1MHz. The IIc+, IIgs, Laser 128 or even machines with a Zip chip could all use a patched DOS to use a different interleave and high speed cpu during decoding.
Apples had hard drives attached to them before the +4 even existed and you have different transfer rates. Early drives used custom DOS but later things with through Apple's DOS. Stuff loads almost instantly from my CFFA board using DOS 3.3 or ProDOS.
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