Re: ProDOS, 5.25" drives, and 35/40 tracks

[Rubywand <rubywand@swbell.net>]

Benjamin Summers writes ...
> 
> If Apple II 5.25" drives have the ability to read and write 40 tracks
> instead of the usual 35 (several software patches are available), can anyone
> tell me why in the world Apple didn't write ProDOS to take advantage of
> this??  I mean, as if the single-sided nature of the drives wasn't enough,
> Apple seems to have placed artificial limits on storage space.
>

 ....

     Probably, Apple should have gone to 36 Tracks when it upgraded to
DOS 3.3. Practically all 5.25" drives seem to be able to handle 36
tracks; and, the extra 16 Sectors would have been nice to have as a
standard feature.

     40 Tracks is different. Many 5.25" drives will not work reliably
for 40 Tracks. At the time ProDOS was first released, the standard
number of tracks on a 5.25" Apple II diskette was pretty well 'set in
stone' at 35 and most A2 drives in use were still not good for more than
one or two extra tracks.

     Changing the standard to, say, 36 would have given us an extra 4k
of storage but at the price of incompatibility with all sorts of
Track/Sector-oriented utilities. Since a really significant boost to 40
Tracks and an extra 20k of storage was not feasible, Apple stuck with
the 35-Track standard and avoided a bit of hassle.

     Another factor Apple may have considered is that larger-format 3.5"
drives and diskettes were in the works. Also, ProDOS made it easy to
'put everything' on a hard disk. Squeezing a bit of extra storage from
5.25" diskettes at the price of compatibility problems makes little
sense if you expect everyone to soon be using 3.5" diskettes and hard
disks. 

     
     

Rubywand