Re: Ewen Wannop's ProDOS Directory Info

["John B. Matthews" <nospam@nospam.com>]

In article <4033D78A.931F3ECB@swbell.net>,
 Rubywand <rubywand@swbell.net> wrote:

> Bill Garber writes ...
>>[perils of extending top level directory]
>      Interesting info. Wonder if Ewen tried moving the Volume Bit Map so that
> he would have contiguous Volume Directory blocks. If he did, then the failures
> may have been due to Appleworks's assumption that the VBM would start at Block
> 6. It would be writing file entries to Block 6 _and_ marking the VBM at Block
> 6-- sure to mess up the directory.

It's possible, but the location of the pointer to the first VBM 
block was well documented in the ProDOS technical reference 
manual. For example, see procedure FreeCount in the code at

http://www.wright.edu/~john.matthews/apple2.html#df

I always speculated that the limit was a compromise to 
accomodate 140K floppies.

> Rubywand

John
----
jmatthews at wright dot edu
www dot wright dot edu/~john.matthews/