Re: DOS 3.3 disk usage

[pausch@saaf.se (Paul Schlyter)]

In article <4694f34c$0$14095$742ec2ed@news.sonic.net>,
Andy McFadden  <fadden@fadden.com> wrote:

> Simon D. Williams <bb065@chebucto.ns.ca> wrote:
>> Thanks for the explanation. I was using DOS3.3 in hopes of having more free
>> spaceto play with, however my approach is eveidently not going to work. I
>> have 64 x 1K files which I need to load from disk (not all at the same
>> time!). Is it possible then to save them all to a single 64K file and then
>> access 1K chunks... I believe this can be done in ProDOS, but is it possible
>> in DOS3.3??
> 
> Not from BASIC, unless it's text data (no zero bytes).

...and not from any other language either, as long as you're using the
DOS 3.3 command interface (i.e. "printing" Ctrl-D followed by the DOS 3.3
command and terminated by a CR).

You must use the less well documented File Manager interface of DOS 3.3
to do random access I/O of binary data on DOS 3.3 files.  But if you
use this interface, you can access any DOS 3.3 file type randomly
with binary data.

Apple Computer never published any information about the File Manager
interface.  The best published description about that interface can
probably be found on the book "Beneath Apple DOS".  It's available
for download as a PDF file - just Google for:

    "Beneath Apple DOS"   pdf

and you'll soon find it.

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