Date   : Mon, 20 Jun 2005 17:07:48 +0100
From   : Mike Howard <aixguru@...>
Subject: Re: A couple of questions - Econet & 1770 Disc Interface

Chris Johns wrote:
> On Mon, 20 Jun 2005, Mike Howard wrote:
> 
> 
>>I also have an Issue 7 BBC/B who's history I know little about (I
>>believe it came from the Depatment Of Chemical Engineering at Nottingham
>>University) and cannot get the disc interface to work. I'm using a known
>>good floppy drive, known good disc interface, known good 7438s and the
>>link is fitted at IC86. IC87 is fitted with a 74LS123 but unfortunately
>>not socketed.
> 
> 
> You need to modify the 1770 interface to fit it if one of the ICs is
> present and not socketed. There is a pad on the corner of the interface,
> the track between the two pins needs to be broken and one side soldered to
> a pin on IC87.
> 
> I don't recall the exact details, they should be in the 1770 fitting
> guide, I have a copy but its 200 miles away - I can find out when I'm next
> home if required.

Thanks Chris but the procedure you're refering too applies when no 
socket is fitted at IC86. The non-socketed IC I was refering to is IC87 
and I only refered to is because it means I can't easily replace the 
74LS123 present there with a known good one.

One thing I didn't mention (I doubt it has any bearing) is that it has a 
SADFS 2.12 rom fitted (along with SDFS 2.12 and BASIC4).

Cheers,
Mike.
-- 
Mike Howard                   aixguru at blueyonder dot co dot uk
Eccleston                      (Hotmail Reply-To is a spam trap)
UK