Date   : Sat, 01 Jan 2011 23:35:46 +0000
From   : jgh@... (J.G.Harston)
Subject: Patching a CF card patched ADFS

Rick Murray wrote:
> On 02/01/2011 00:02, J.G.Harston wrote:
> That said, Acorn do have to shoulder some blame for allocating a wodge
> of types to files which do not actually need a specific type. I don't

There was a big reallocationing sometime in the early 1990s which
pruned Acorn's huge claimed chunk an rationalised things a bit.

> respective program, having no double-click action whatsoever. For those,
> &FFD would suffice.

Acorn not taking their own advice? Ooo, never! :)

>> filing system numbers and that things like IDE/SCSI/CDROM/etc filing
>> systems should be device drivers to ADFS, not filing systems in their
>> own right.
>
> You mean like how DOSFS works?

A bit like that, and the way ADFS (IDE and ST506 drivers) and FileCore
(the file system structure) work.

> I think some parts of the filesystem code
> were notoriously complicated.

HardwareDriverX_ReadSectors, HardwareDriverXX_WriteSectors is all
that's needed. The whole point of writing device drivers instead of
whole filing systems is to leave all the complexity higher up in
pre-existing code, just like CFS/ROMFS on the BBC. I can imagine
hearing Acorn saying "...but you've just duplicated xxx-thousand
lines of pre-existing code to re-invent a pre-existing wheel!"

> disc, or stupidly-long filenames as you might encounter on a CD-ROM for
> a Windows platform?

A single common CDROMFS instead of at least three different CDROMFSs.

> It's all well Acorn making proclamations,

Quite a bit of it was Acorn letting things run away from them too
quickly.

> And that's why if ADFS thinks it should have been the base (instead of
> FileCore), it should have been ahead of the game, not behind it.

ADFS just provides drivers to IDE and ST506 drivers, FileCore
defines the file system structure. FileCore "exports" the name
of the device driver (eg ADFS) to FileSwitch as the filing system
name.

I've gone blurry-eyed working my way through FileSwitch/FileCore/
ADFS code and documentation way too many times. ;)

-- 
J.G.Harston - jgh@...