Re: Apple ProDOS CP/M disk & file utility

[pausch@saaf.se (Paul Schlyter)]

In article <9d6n0u$411$1@vax.area.com>,
Matt Ackeret <mattack@vax.area.com> wrote:
 
> In article <9d4cri$f3s$1@merope.saaf.se>, Paul Schlyter <pausch@saaf.se> wrote:
>> Probably the "Pascal Micro ENgine" failed for the same reason: slowness.
> 
> Well, presumably it's faster than emulating the Pcode.
> 
>> BTW of all the Apple OS'es DOS, ProDOS, Pascal and CP/M, Apple Pascal
>> had the most primitive file system: it was the only file system which
>> required the files to be contiguously stored on the disk.  That's why
>> the Apple Pascal system had a "crunch" command, which moved files as
>> needed to merge all free parts of the disk into one contiguous space:
>> on the other Apple OS'es this wasn't needed as they could handle disk
>> fragmentation.
> 
> Is this really only true in the Apple Pascal environment?
> 
> I thought it was a design decision which affects all UCSC Pascal 
> implementations.
 
Probably true.
 
> Besides, having to K)runch manually was a pain, but it also then made loading
> faster compared to noncontiguous files on other OSes.  (Plus, isn't the
> absolute minimum load time lower than on other Apple II file systems?)
 
Yes, it is, and this is mostly due to the Apple Pascal's RWTS, where
the read routine did read one track at a time while the disk revolved
once!  THe conversion from nibbles to bytes was done "on-the-fly",
while nibbles were read off the disk.  In all other Apple II OS'es
the nibbles of one sector were first read into a "nibble buffer", and
then these nibbles were converted to bytes, while parts of the next
sector passed under the disk head without being read.
 
And of course having a primitive file system helps in getting fast
file transfers: it takes time to read and process subdirectories,
allocation maps, etc - in particular on slow floppy disks.

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