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From: adrie@philica.ica.philips.nl (Adrie Koolen)
Newsgroups: comp.os.minix
Subject: Re: Larger / non-std fd formats (ST).
Message-ID: <816@philica.ica.philips.nl>
Date: 21 May 91 09:06:02 GMT
References: <3115@krafla.rhi.hi.is> <3143@krafla.rhi.hi.is> <813@philica.ica.philips.nl> <3157@krafla.rhi.hi.is>
Reply-To: adrie@beitel.ica.philips.nl (Adrie Koolen)
Organization: Philips TDS, Innovation Centre Aachen
Lines: 32

In article <3157@krafla.rhi.hi.is> adamd@rhi.hi.is (Adam David) writes:
>I agree that compatibility between different types of drives / controllers is
>a potential hazard well worth being aware of. Modern drives conform to a
>higher standard of design / manufacture in this respect.

`Modern drives' are not yet old, but they will be somewhere in the future.
When current modern drives get old, they won't get better; they probably run
worse as they get aged. Also, the diskettes they've now written, are also
worn-out after a few years. Your observations are based on `modern' drives
with `new' diskettes, which you instantly read back after you've written them.
Of course, I can't exactly tell how much the current drives and diskettes
deteriorate in the future, but neither can you! The only precaution you can
take is not to push disk formatting too far!

>An example was mentioned of failing to read old Commodore disks on an IBM PC.
>Both of these systems have known shortcomings in the disk controller circuitry,

They worked properly with diskettes, formatted according the IBM system-34
(MFM) specs!

>and this was before compatibility became a real issue. 10-sector DD disks
>shouldn't really run into any problems between different systems in use today.

But what about the systems, in use in the future? I've diskettes, formatted on
my Apple II+ some 7 years ago and when I tried to read them lately, much of
the diskettes gave read-errors. Now I know that diskettes need not last for
more than 5 years, but I can GUARANTEE that diskettes, formatted closely to
the limits of the specs, will give you more read problems and earlier than
diskette, formatted according the MFM specs.

Adrie Koolen (adrie@ica.philips.nl)
Philips Innovation Centre Aachen