Date   : Mon, 30 Mar 2009 14:07:50 +0100
From   : bbcmailinglist@... (Ian Wolstenholme)
Subject: A few Econet questions

I think it was my survey of Econet interfaces (http://www.beebmaster.co.uk/EconetInterfaces.html)
which started off this vicious rumour about the 32-bit Econet interface having
an optional clock generating circuit.

This page is now considerably out of date and contains quite a few errors,
so caveat emptor until I can update it.  Looking at the 32-bit module again,
it seems unlikely that a single 16-pin chip and four links would do the job and
it's more likely as others have said that it is to allow a DIL 26LS30 to be used
in place of a surface mount one.

The circuit diagram for the 32-bit module is in the Econet Design & Installation
Guide and as soon as I've relocated it, I'll dig it out and hopefully have the
conclusive answer.

Best wishes,



Ian
  
----- Original Message -----
From: Pete Turnbull [mailto:pete@...]
To: bbc-micro@...
Sent: Mon, 30 Mar 2009 10:47:12 +0100
Subject: Re: [BBC-Micro] A few Econet questions

On 30/03/2009 09:58, Phil Blundell wrote:
> On Sun, 2009-03-29 at 23:57 +0100, Pete Turnbull wrote:
>> If this is what I think it is, it's the collision detect IC, the inputs 
>> of which are connected to the data+ and data- lines.  Not fitted on some 
>> variants of the board, because after selling lots of modules with the 
>> collison detect, some bright spark in Acorn figured out that the 
>> software took care of it anyway, and the hardware wasn't needed.
> 
> I thought the business with removing and then reinstating the
> collision-detect circuitry happened much earlier; my recollection was
> that, having been included in the Beeb interface circuit, it was left
> out of the first version of the Master plug-in module but then later
> added back on for the reasons you mentioned.

That's correct, but who knows what Acorn may have got up to with 
ARM-based machines ;-)  Someone mentioned a surface-mount device; I've 
not been able to look closely enough at the photo but it's possible that 
there was an option for either SMT or DIL on the board.

-- 

Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York

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