Re: 1571 blocks free

From: Spiro Trikaliotis <ml-cbmhackers_at_trikaliotis.net>
Date: Sun, 26 May 2013 20:14:54 +0200
Message-ID: <20130526181454.GD9312@trikaliotis.com>
Hello,

only an educated guess: ;)

* On Sun, May 26, 2013 at 07:46:27PM +0200 silverdr@wfmh.org.pl wrote:
> Does anyone know (without digging the rom disassembly) if 1571, when
> calculating "BLOCKS FREE" value, takes into account what is stored in
> second BAM sector (53,0) for track 53? All sectors of this track
> should be allocated anyway, which means that under normal
> circumstances (a fully valid and non-custom, non-corrupted disk) it
> should not matter. But what if someone decided to make some use of
> those wasted sectors and modified the BAM accordingly?

I can only tell for the 2031/1540/1541 out of my head: The 1541
calculates the blocks free that are actually free. That is, it takes the
BAM into account, and does not use any pre-knowledge (other than knowing
that 18/0 contains the BAM, that is).

I would expect the 1571 to behave accordingly. But: I do not know for
sure, it is only a guess.

> Also: will it issue ILLEGAL T/S if a file is chained to track 53?

Again: The 2031/1540/1541 do not perform any such checks. Thus, chaining
a file to 18/x is no problem there. Again, I would expect the 1571 to
behave accordingly.


Having said all this: It should be rather easy to test this, or am I
missing something?

Regards,
Spiro

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Received on 2013-05-26 19:01:03

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