Date   : Thu, 02 Apr 2009 21:41:03 +0100
From   : mfirth@... (Michael Firth)
Subject: A few Econet questions

> ----- Original Message ----- 
> From: "Ian Wolstenholme" <bbcmailinglist@...>
> To: <bbc-micro@...>
> Sent: Monday, March 30, 2009 2:07 PM
> Subject: Re: [BBC-Micro] 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 This page is now considerably out of date and contains quite a few errors,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.

It wasn't just your site, I'm sure I read it somewhere else too (but I can't 
remember where at the moment)

Given that your site is probably one of the top 3 with Econet information 
out there, I guess its not surprising I referenced it!

The mystery chip is definitely an option to allow the use of a DIL driver 
chip - possibly due to supply problems, or possibly to allow it to be 
replaced in the field if it failed.

The schematic of the new A3020/A4000 module is in the technical drawings 
archive available from here:
http://acorn.chriswhy.co.uk/docs/Acorn/Manuals/Acorn_A3010A3020A4000TRM_Drawings.zip

This schematic confirms that IC4 is also for a 26LS30 chip, and is wired in 
parallel with IC7.

I've extracted the relevant PDF, and uploaded it to 
http://www.firths.org/bbc/Acorn_A3020A4000_EconetModule.pdf, in case anyone 
wants an easy link.

The bill of materials for the module is in the Technical Reference Manual, 
which I thought was also on Chris's site, but is actually here:
http://www.drobe.co.uk/reference/trm.php

I guess the final question is whether anyone can tell from this schematic 
whether this module has or doesn't have the collision detection hardware?

Regards

Michael