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From: syswtr@iowasp.physics.uiowa.edu
Newsgroups: comp.os.cpm
Subject: Re: 8 meg limit
Message-ID: <1991Jan24.113358.460@iowasp.physics.uiowa.edu>
Date: 24 Jan 91 17:33:58 GMT
References: <D4J8V2w163w@cynic.wimsey.bc.ca> <1991Jan23.223619.49@skyler.mavd.honeywell.com>
Organization: Department of Physics and Astronomy, University of Iowa
Lines: 16

> pevans@cynic.wimsey.bc.ca (Phillip Evans) writes:
>> Where did/does the 8 meg limit on logical disk size in CP/M come from?

  NOte that this restriction is removed in CPM3 and MPM2.  The file
size restriction is limited by the 16 bit record pointer in MPM2
(I haven't combed the CPM3 manuals that closely), but the logical
device size is limited by the cluster size.  Device size is 
expressed in terms of the number of clusters, so the maximum
device is 32767*16384 (or 65535*16384) as the largest allocation
cluster is 16K bytes.
  When you get these large devices, however, MPM2 signifigantly slows
down when doing any directory operations as it scans the (potentially)
large directory.  A little work with caching the directory can make
a world of difference...

Willy