Date : Thu, 09 Feb 2012 16:24:47 +0100
From : kortink@... (John Kortink)
Subject: 32016 + ADFS 1.40 (take 2)
On Mon, 23 Jan 2012 22:13:26 +0100, I wrote:
>[...]
>In particular, the 24 uS minimum for 1-byte transfers is
>simply too much for the poor old 6 MHz 16/32-bit monster.
>[...]
As a followup to this : of course, somebody knew ...
Quote from page 351 of 'The New Advanced User Guide' :
'
The original 32016 second processor design was carried
out with the intention of marketing an 8 MHz machine.
Due to the non-availability of the 8 MHz chip sets,
Acorn launched the 32016 with a 6 MHz chip set.
Unfortunately an unforseen problem arose with the
use of the normal ADFS software and the slower 32016's
which meant that a special version of ADFS had to be
written for use with the slower machines. The changes
which had to be made meant that there was no room to
include the floppy disc drivers in this version of
ADFS [ed: 1.40] (i.e. it can only be used with a
winchester hard disc).
The best way to circumvent this problem is to replace
the 6 MHz chip set with 8 or 10 MHz chips and to
replace the 12 MHz crustal with a 16 or 20 MHz one
(the crystal frequency is halved for the main clock
frequency). Once this is done normal ADFS software
works perfectly well with floppy or hard discs.
'
Live and learn.
The 'no room to include the floppy disc drivers' claim
is pretty much bogus, though. The differences between
ADFS 1.40 and the nearest other versions on model B
and Master are pretty minimal, really. They could have
easily fitted the requisite changes in ADFS 1.30 and
1.50 without sacrificing anything. Instead, apparently,
they chose to clobber the floppy specific code, and
(in the case of the Master version) replace it with
some dubious debugging crap that messes with the
user via (!), larded with 'Hugo woz here' messages.
It all looks pretty haphazard, if you ask me ...
Must try the 8/10 MHz thing sometime though ...
John Kortink
--
Email : kortink@...
Homepage : http://www.inter.nl.net/users/J.Kortink