Re: Apple Disk Drives

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

william strutts <wrstrutts1@home.com> wrote:

> I recall the feature to format a single sided disk in Finder 6.0
> but I don't recall it being in Finder 7.0.1.  Who would want
> to format a 400K disk anyway from a Mac Plus or better?
> It wouldn't make much sense so effectively the feature was
> there only for backward compatibility.

Formatting a 400K disk to send to someone with an older machine would be
the obvious use.  It is also worth noting that you can connect a 400K
drive to a Mac Plus (probably also an SE or II, but I don't know about
later models).

The disk initialization package was in ROM, so I suspect it may have
been tied to specific hardware more than system software versions.
Apple could have patched it in System 7 or later to remove the option
for 400K formatting.

> I used System 7.0.1 on my Mac Plus until about 1996.  That was the last
> release of the OS that supported the Mac Plus.

The last system version which works on a Plus is 7.5.5.

(7.6 dropped support for all 68000 and 68020 machines, plus 68030
machines which were not "32-bit clean", i.e. the IIcx and SE/30.)

> Maybe the later releases only supported the reading of the disk or it
> would only ask the Single/double question only when a DSDD disk was
> inserted.

That is what I would expect.  There is no way for the hardware to detect
a 'single sided' 3.5" disk, so it would have to ask whether you wanted
to format as 400K or 800K.

With a SuperDrive, more recent system software gives the option of
formatting a double density disk as HFS with 720K or 800K formats,
MS-DOS (720K) or ProDOS (800K).

For a high density disk, the choice is between HFS, MS-DOS or ProDOS
(all 1.44M).

> The question would probably have been 1.44/800K on newer Macs when
> you inserted a HD disk

Nope.  There is an extra notch on a high density disk, so the system
software can determine the density automatically.