[comp.sys.mac] Multifinder floppy copying/swapping...

harrow@bagels.dec.com (Jeff Harrow, NCSE BXB1-2/E02 DTN=293-5128) (11/11/87)

I've noticed  that when using the released version of Multifinder
to copy diskettes  on  a  single-floppy  Mac  II,  I have to swap
diskettes several times during  the process.  Given that this Mac
II has 2 Meg.  of memory and NO other tasks were launched, why is
this necessary, since all of the  800K  diskette  should fit into
the available memory?

Apple, any ideas?

Jeff Harrow

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lsr@apple.UUCP (Larry Rosenstein) (11/19/87)

In article <8711111557.AA22388@decwrl.dec.com> harrow@bagels.dec.com (Jeff Harrow, NCSE BXB1-2/E02 DTN=293-5128) writes:
>I've noticed  that when using the released version of Multifinder
>to copy diskettes  on  a  single-floppy  Mac  II,  I have to swap
>diskettes several times during  the process.  Given that this Mac

I talked to a Finder person about this, and I think I have the story.

The Finder uses a fixed size copy buffer (200K I think), unless the copy
involves removable media.  Then it uses as much memory as it can get, either
from its own heap or from Multifinder temporary memory requests.

The other factor that comes into play is that there is a limit on the number
of file forks the Finder copies at once.  This limit is currently 40.  So if
you copy 30 files, each of which has a data fork and resource fork, the
Finder will copy the first 20 (40 forks in all) in one pass and the second
10 in another.

So if you copy disks with lots of small files on them or lots of files with
both a data fork and resource fork (eg, MPW source files), you can encounter
some extra disk swaps.

I hope this answers the question.

-- 
Larry Rosenstein

Object Specialist
Apple Computer

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