Re: Auto Boot

From: Ingo Korb <ml_at_akana.de>
Date: Sat, 06 Apr 2013 01:19:06 +0200
Message-ID: <uip40muqd.fsf@dragon.akana.de>
William Levak <wlevak@SDF.ORG> writes:

> 0:* is NOT always the first file.  It's the last file referenced.  It's
> the first file only if the drive has not referenced a file previously.

The 1541 explicitly checks if the first character of the string received
from the computer is a * and only in this case it loads the last file it
opened by re-using the drive/track/sector numbers still stored from the
last access.

The code for this is at $D7BF in the 1541 ROM, see
http://unusedino.de/ec64/technical/aay/c1541/ro41d7b4.htm for a
disassembly - the comparison with '*' is the first instruction on
the next page.

> 0:?* always gives the first file.  The pattern matching ? forces it to
> go back to the beginning of the directory to do the search.

If none of the special cases apply, file name matching always starts at
the beginning of the directory. This means that :* or 0:* will always
(attempt to) open the first file in the directory.

-ik

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Received on 2013-04-06 00:01:54

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