Date   : Wed, 08 Nov 2006 18:38:08 -0000
From   : jason.watton@... (Jason Watton)
Subject: DFS on 3.5inch - Is this supposed to work?

Hi Jules,

I don't want to bore everyone with detail so I'll sum up and shut up - and 
take this off-list if it gets too technical.

My plea is to ease off on heavy "It almost certainly won't work" statements 
of fact.

> OK, so my perspective:
>
> I do a fair bit of data recovery work from old FM-only systems. I talk to
> quite a few people who do a *lot* of data recovery work from old FM-only
> systems as data recovery is their primary source of income.

I'm surprised any professional data recovery outfit would use a 'standard' 
PC - custom hardware (like the CatWeasel) would be far more suitable for a 
serious/professional user. If you're doing this a lot, Jules, take a look...

> Most PCs *will not* work properly with FM disk encoding. For a machine 
> built ...

I really want to know what "most" and "work properly" mean (technically!).

What software do you use? Have you direct control over the FDC? Have you 
exhausted all the possibilities on a PC that "does not work" that it's not 
just a software problem? **You're not using the BIOS, are you**?

I want to post this to the List so it's recorded but I'm really after a 
detailed technical response which can be off-list...

> So, across the whole spectrum of PCs, according to the experience of 
> myself
> (and others even better qualified than me to say) most *will not* happily 
> read ...

I want to know what 'most' means. I *would* appreciate a list of the PCs 
that don't work with FM simply for my records, but I realise that's a bit 
much to ask!

> Regarding FM ability but BIOS/controller which only handles 512 byte 
> sectors -

IMHO the BIOS only contains parameters for the 'standard' DOS formats, and 
if you talk to the FDC directly the BIOS can be safely ignored.

Which gives me this final thought... Are PCs being branded 'not working' 
based on poor BIOS support? For all of the above, I'm not talking about 
using DOS INTs and the BIOS to handle alien disk formats - I'm talking about 
taking over complete control of the PC's FDC and programming the chip 
directly. Nothing less than this is of any consequence.

If anyone can provide evidence/statistics I *would* like to know... (plus 
the software used!).

J.