Date   : Sat, 12 May 2001 07:28:54 +0100
From   : Mike Tomlinson <mike@...>
Subject: Re: 1770 Disk Interface

In article <8F55B1918087D4118BCB00508B0CCEBB01921A3B@...>,
Saddler, Chris <CSaddler@...> writes

>Has anyone every tried to recreate a 1770 (or 1772) based disk interface
>daughter board for the BBC Model B?

I haven't, but have seen home brew ones.

> i.e. make a PCB based on the schematic
>shown at http://members.magnet.at/marku/bbc/hardware.htm

Don't forget that in addition to the circuit, you will need two wire
links, two 7438 buffer chips (74LS38 must not be used) and a DFS ROM.
There may be other bits - I can't remember - though Mark's site also has
the fitting instructions somewhere with a list of parts.

I'd have thought the most difficult bit to find might be the 40 pin
header to plug the assembly into the 8271 socket.  If you can't find
this, have a look in the RS catalogue for 40 pin ribbon cable headers.
Perhaps you could put the board on a short length of ribbon cable.

Wouldn't it be easier to buy a second hand Beeb with one fitted and use
that or salvage it?

>I'd be interested in upgrade my 8271 based disk interface to the 1770. Also,
>does the circuit remain the same for the WD1772 based interface?

Yes.

>If I get a positive response to this, my next question will be where to get
>a WD1770/1772?

CPC (www.cpc.co.uk) used to carry them some years ago.

-- 
"Security-wise, NT is a server with a 'Kick me' sign taped to it."
                      - Peter Gutmann