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From: doner@henri.ucsb.edu (John Doner)
Newsgroups: comp.sys.mac.system
Subject: Re: Boot blocks and open files
Message-ID: <10688@hub.ucsb.edu>
Date: 19 Apr 91 16:30:21 GMT
References: <1991Apr18.123602.780@iowasp.physics.uiowa.edu>
Sender: news@hub.ucsb.edu
Reply-To: doner@henri.UUCP (John Doner)
Organization: University of California, Santa Barbara
Lines: 29

In article <1991Apr18.123602.780@iowasp.physics.uiowa.edu> kistler@iowasp.physics.uiowa.edu writes:
=>What's the relation between boot blocks and the maximum number of open files
=>allowed?
=>
=>Context:  On a couple of occasions, I've had about 10 (I think) files open in
=>a single application, like MS Word or Excel.  To print any single file, I
=>would have to close 2 or 3 of the files or I would get an alert that says
=>"too many open files."  I have also noticed in some documentation for some
=>programs I don't currently use that, to increase the max number of open files,
=>a user should use something like the "power user" settings of Suitcase to boost
=>the number of boot blocks.
=>
=>So does a boot block have space in it for a file buffer, and each boot block
=>corresponds to being able to open a file, with maybe a few for system overhead?
=>As secondary question:  how come printing is apparently equivalent to a couple
=>of open disk files?

The boot blocks are the first couple of sectors on your startup disk.
They are read by the ROM to determine various parameters, such as the
name of the Finder, the debugger, and among other things, how big to
make the table of File Control Blocks.  This controls the maximum
number of open files.  On current systems, I believe, the maximum is
set at four times the number found in the boot blocks.  The boot
blocks can be edited with the FEdit utility, and other disk editors.
Open the startup volume and choose Edit Boot Blocks from the File
menu.  You can double the Max Open files item, or set it even larger.

John E. Doner	doner@henri.ucsb.edu	(805)893-3941
Dept. Mathematics, UCSB, Santa Barbara, CA 93106