Date   : Tue, 16 Sep 2008 08:13:45 +0100
From   : info@... (Sprow)
Subject: Question about 1770 DFS interface testing it on a B

In article <080913195513@...>,
   Jonathan Graham Harston <jgh@...> wrote:
> > Message-ID: <18FD0346D52E4F63AF33DFF6DFBAF698@...>
>  
> "Mark Haysman" wrote:
> > *DUMP isn't in the OS1.20, as on a standard machine it reports Bad 
> > Command.
>
> I'm tempted to look into it and see if DNFS can be patched to
> uncouple UTILS from DFS.

If you can suffer the loss of RAM its check for 8271 fitted is looking at
the bottom 2 bits of the status register at &FE80 being clear.

Using pin 9 (nRD) you could drive the 2 lines low with a spare 74LS245 from
the junk box pushed into the appropriate pins of the socket,
Sprow.