Re: BAM HPFS

[dempson@actrix.gen.nz (David Empson)]

Gregory Weston <uce@splook.com> wrote:

> In article <3cjVf.753$t22.146@dukeread08>,
>  "Jack Tseng" <tseng4@hotmail.com> wrote:
> 
> > You know about Commodore 1541's BAM, and OS/2's HPFS. What is it called for
> > Apple II ProDOS?
> 
> I only ever heard it called the ProDOS file system. I don't see any 
> specific name given in my copy of the ProDOS 8 Technical Reference 
> Manual.

It was the same file system used earlier by Apple /// SOS, so perhaps it
should be called the SOS file system. I've never seen it described that
way in an Apple II context, however.

In later systems which had the ability to support multiple file systems
(e.g. GS/OS, and Mac OS with the ProDOS file system extension), the file
system was always referred to as "ProDOS".

There were several extensions to ProDOS over the years, such as GS/OS
adding resource forks and the ability to have lower case in filenames,
but the underlying file system was still called ProDOS, and was still
compatible with 8-bit versions of the operating system as long as
resource forks were avoided.

> > eariler MacOS 7.5 to 9???
> 
> The first Mac file system was MFS. M for Macintosh. Completely flat file
> system with an illusion of hierarchy maintained by the UI.

Also noteworthy that it was used on 400K 3.5" disks (single sided). I'm
not aware of it being used on another type of disk, but I wasn't using
Macs at the time so might have missed something.

I don't recall what file system was used on the Lisa. Anyone know?

> In 1985 (System 3.2, IIRC) they introduced HFS. H for hierarchical. 
> Introduced a few other benefits, but also some new restrictions. 
> Probably the most annoying is that the maximum length of a file name was
> cut in half.

Originally used on 800K 3.5" disks (double sided), also supports much
larger volumes, but is limited to about 65000 allocation blocks per
disk, so the amount of disk space wasted per file gets unreasonable up
the gigabyte realm.

When formatting a floppy disk in systems which supported both file
systems, the "single sided" or "double sided" question was also choosing
which file system to use on the floppy (MFS for 400K, HFS for 800K).
There was no standard way of creating a 400K HFS floppy.

> Mac OS 8.1 brought HFS+. A whole raft of new features in the file 
> system, many of which weren't actually leveraged by the OS immediately.
> The biggest benefit for most people was probably that they raised the
> upper limit on the number of allocation blocks, which meant no more 
> half-meg grocery lists on large volumes. Some of them, in fact, only 
> used in the last couple of years.

After introducing HFS+, Apple also used the names "Mac OS Standard" for
HFS and "Mac OS Extended" for HFS+.

-- 
David Empson
dempson@actrix.gen.nz