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From: sb@pro-generic.cts.com (Stephen Brown)
Newsgroups: comp.sys.apple2
Subject: ProDOS Question
Message-ID: <507.infoapple.net@pro-generic>
Date: 6 Jun 90 06:57:46 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 24

I have a couple questions about ProDOS. I have been reading my trusty Beneath
Apple ProDOS, and have become confused.
 
When it talks about the ONLINE (return names of one or all online volumes) MLI
call, it says that it will return the name of 1 volume if a specific unit
number is specified, in which case a 16 byte buffer is needed. It then goes 
on to say that if a zero (non specific) unit number is used, all volumes' names
will be provided, and a 256 byte buffer will will be needed. But I thought only
14 volumes were supported, which requires 14*16=224 bytes! I checked the
reference card, and indeed, in the system global page, there are 16 places in
the device driver address table, but two (for slot 0) are reserved. 
Why is a 256 byte buffer needed?
 
Also, in the discussion about the OPEN (open a file) MLI call, it says "more
than one OPEN may be issued to the same file is the file's access is WRITE
disabled (read only file)".  Why would you possibly OPEN the same file more
than once?

Thanks!
Dazed & Confused. Stephen Brown (Willowdale, Ontario, CANADA)

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