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Groups > comp.sys.apple2.programmer > #1306

Re: 80 column card RAM disk

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On 01/09/2014 7:44 PM, David Empson wrote:
> One other point I forgot to mention: I expect that the main reason
> blocks 4-7 are reserved is to deal with software which expects most of
> those to be the root directory and volume bitmap, and so that some of
> the memory addresses line up nicely (once you get beyond the complex
> remapping).

Except that one every other ProDOS volume that is less than 2 MB in 
size, the first block available for storing files is block 7, not block 
8, so I still don't understand why block 7 is marked as used.

Perhaps simply because they needed to drop another block as they didn't 
have another 512 byte chunk of memory to use so tossed a coin to 
determine whether to drop block 7 or block 125.  Or perhaps someone said 
that the first 7 blocks were already used (blocks 0 to 6) and someone 
else assumed that meant that the first available block would be 8.  :)

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80 column card RAM disk ivan@ivanx.com - 2014-09-01 15:05 -0700
  Re: 80 column card RAM disk dempson@actrix.gen.nz (David Empson) - 2014-09-02 11:41 +1200
    Re: 80 column card RAM disk dempson@actrix.gen.nz (David Empson) - 2014-09-02 11:44 +1200
      Re: 80 column card RAM disk Jeff Blakeney <CUTjeffrey_blakeney@yahoo.ca> - 2014-09-02 07:53 -0400
    Re: 80 column card RAM disk Jeff Blakeney <CUTjeffrey_blakeney@yahoo.ca> - 2014-09-02 07:46 -0400
      Re: 80 column card RAM disk dempson@actrix.gen.nz (David Empson) - 2014-09-03 14:15 +1200
        Re: 80 column card RAM disk Jeff Blakeney <CUTjeffrey_blakeney@yahoo.ca> - 2014-09-02 22:36 -0400
          Re: 80 column card RAM disk Antoine Vignau <antoine.vignau@laposte.net> - 2014-09-05 14:27 -0700
  Re: 80 column card RAM disk Jeff Blakeney <CUTjeffrey_blakeney@yahoo.ca> - 2014-09-01 20:09 -0400

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