Date   : Mon, 22 Jul 2002 21:47:25 +0100 (BST)
From   : Andrew Benham <adsb@...>
Subject: Re: solidisk dfdc

On Mon, 22 Jul 2002, W.Scholten wrote:

> Does anyone have the installation instructions?

No, but I've found some old hand-drawn circuit diagrams (reverse
enginering!).

> I want to know where the two leads go on IC86 & IC87 (it's a different
> board to that on the 8bs website), and what to do if there's no 8271 DFS
> fitted and what if there is (any connecting jumpers as for the standard
> DDFS? Are the leads not needed if a full 8271 DFS is already installed?)

The lead connected to pin 18 on the 1770 socket needs to go to
IC86 pin 1.
The lead connected to pin 19 on the 1770 socket needs to go to
IC87 pin 5 or 9.

>From what I recall, the DFDC board assumed that one already had the
8271 disk upgrade fitted.

My recollection of these boards is not 100% - the circuit diagrams
I drew are dated 1988 and 1989, and I've not seen one of these
boards since then.


> And can one identify visually if solidsk DDFS & DFDC boards are the
> later Acorn ADFS compatible versions? (i.e. able to use the Acorn ADFS
> rom)

DDFS
----

The Mark 1 DDFS board has 1 x 74LS374.

The Mark 2 DDFS board (which has the 1770 at the same addresses as the
model B with 1770 DFS) has 1 x 74LS374 and 1 x 74LS136.


DFDC
----

The Mark 1 DFDC board has 3 x 74LS157 and 1 x 74LS374.

The Mark 2 DFDC board (which has the 1770 at the same addresses as the
model B with 1770 DFS) has 3 x 74LS157, 1 x 74LS374, and 1 x 74LS136.


-- 
Andrew Benham     adsb@...           
Southgate, London N14, United Kingdom

The gates in my computer are AND OR and NOT, not "Bill"