Date   : Tue, 01 May 2007 12:37:30 +0100
From   : pete@... (Pete Turnbull)
Subject: Arthur on 5.25" media...

On 01/05/2007 11:46, Jules Richardson wrote:

>>> I always thought that Arthur was released on 3.5" media for the ARM machines,

>>> not 5.25" - I didn't think there even *was* an Arthur-capable system
which had 
>>> a 5.25" drive as standard. A500 second processor, maybe?
> 
> I was just quickly poking around the disk images with a hex editor and found 
> the following:
> 
> 0001e600  64 72 69 76  65 20 35 0d  2a 7c 20 52  75 6e 20 6f  drive 5.*| Run o
> 0001e610  6e 20 42 42  43 20 77 69  74 68 6f 75  74 20<41>35  n BBC without A5
> 0001e620  30 30 20 73  77 69 74 63  68 65 64 20  6f 6e 0d 2a  00 switched on.*
> 
> ... so I suppose that clears that one up :-) Anyway, going by the hex dumps 
> the disks do indeed appear to at least be related to early ARM stuff, so I 
> imagine they really are what they say on the labels.

I was going to reply to say I'd expect it was for an A500 but you beat 
me to it.  The A500 is best thought of as a sort of prototype Archimedes 
that used a Beeb as an I/O processor.  I still have one of the Tube 
podules that the A500 used.  Anyway, this is very similar to the way a 
second processor (aka "host processor") used the Beeb ("I/O processor"), 
but at different stages in the development, different amounts of the I/O 
were passed off to the Beeb.  Early on, just about everything was (like 
a normal second processor) but as different parts of the system were 
developed, the A500 had more and more of its own I/O on board.  The 
Beebs in Acorn's lab, of course, would normally have 5.25" disks 
(certainly the ones I saw during development did).

The Arm second processor (aka Arm Evaluation System) didn't run Arthur. 
  It used the BBC MOS like any normal second processor, and had a very 
simple Executive program; a sort of monitor which could set/clear 
breakpoints, dump/fill memory, load, save and run programs, and not much 
more.  If you want to see what the disks were like, the images of the 
disks and the co-processor's ROM are still on my web page at 
http://www.dunnington.u-net.com/public/BBC/ARMeval.html

> According to the card indexes I've got, there should be source to ADFS, BBC 
> MOS,

I'd like to see that sometime.  I was on one of Paul Bond's original 
courses around 1982, and saw parts of the source, and I should have some 
commentary on it somewhere, but I've never seen the whole thing.

-- 

Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York