Newsgroups: comp.sys.acorn
Subject: Re: >>A5000 disc format recognising
From: jwil1@cs.aukuni.ac.nz (TMOTA)
Date: Mon, 13 Apr 1992 22:20:00 GMT
Organization: Computer Science Dept. University of Auckland

ssurawls@susssys1.reading.ac.uk (Mister E) writes:

>It also takes a while to catalogue a floppy disc now as it checks to format

Surely not? Wouldn't the best way be to say "Is this an ADFS disc? Nope...
Oh, well, I'll pass the disc off to another bit of code... Mr. PC Disc reader
... you have a go" etc. etc. so that ADFS discs are recognised just as fast'
as usual, and when you have your PC, Mac, Amiga, Atari ST, UNIX, Cray Y-MP,
and IBM System /360 disc reader modules loaded, it just takes ages to chain
down to the System /360 reader to actually manage to read the 360 disc you
just inserted... Certainly it seems silly to think that ADFS would try
reading ALL these formats before deciding what disc format it actually IS...
it should just be a matter of "Disc reader A failed, try disc reader B"

>first. Then when the directory display appears it looks identical to an ADFS
>display, room for plenty of confusion there! Especially if you copy files such
>as archives or text files, which will be given the correct file type.

Gosh, incredibly confusing, isn't it? I personally name my discs so that
I don't get confused about which one is which. This is very useful, 'cos at
the macintosh end, Mac and IBM discs are read "transparently", so it appears
the same... However, the theoretical idea is that you shouldn't NEED to know
what the disc format is unless you specifically WANT to put it onto some format
-- The only problem is that some formats (IBM) don't suppotr as much info as
others (hence Macintosh's nasty hacks of bunging directories full of
finder-info files onto the discs...)

But basically, to the user, it should look like a DISC. How the computer
makes the disk head warble as it passes over the surface of the disc should
be irrelevant... (especially nowadays when most computers can read most
other computers disc formats)

>>   #2 No, it doesn't recognise the type of disc as per Mac LC's when you
>>      try to format it, i.e. 2D (800K) unformatted disc -> 800K only,
>>      HD (1.44M) -> 800K or 1.44M.
>>      What you select as the format, it will format as requested regardless
>of
>>      the type of disc(unless you select 1.6M format for a 800k disc!).

>If you pop an 800K disc is, you CAN format it to 1.6 megs, and it works. How
>long for, is anybody's guess, but I suppose that if you were to use high
>quality double density discs perhaps it would be allright. Double density
>discs are always much cheaper than high density, a lot of the time less than
>half price, eg I can get good quality discs at 35 pence per disc, and I don't

In my experience, DD discs and HD discs have about a 2:3 price ratio for
a 1:2 (800:1600) capacity ratio... that is, HD discs cost about 2/3 the price
per kilobyte than DD discs...
They are also more convenient - they take up half the amount of space in the
pile on your desk ;-)  and also you can fit large files onto them much more
easily (having 17 megs free on my HDD makes it very very easy to create very
large archives... ;-)

Another advantage of being able to read 800k Mac discs over 720k IBM's is
simply that I quite often get things like 740kB sound samples off the net,
and they just don't fit on the smaller disc... mind you, once I can read 800k
mac discs I will only be using 1.44Meg ones anyway, so I guess it's a moot
point...
-- 
_________________  "I'd like to answer this question in two ways:
  /____ _ _/_ __       First in my normal voice, and then
 // / //_//_ /_/       in a silly, high-pitched whine." (Monty Python)