Date   : Tue, 15 Jul 2003 20:39:57 +0100
From   : Nick B <nickbeee@...>
Subject: 1770 wanted 

Hello,
I'm looking for a 1770 or 1772 chip if anyone has one they want to part 
with?

I've just acquired a B+ which has no DFS of any description fitted, much 
to my surprise. It was interesting to discover it will take either the 
1770 or 8271 on the main PCB. I'd like to fit the 1770 so I can have the 
option of using ADFS too.

I also want to fit some kind of sideways RAM so I propose to fit 62256 
rams in a couple of the ROM sockets and take the write lines from pin24 
on  the 7002  A-D chip.  (pulling up  to  VCC with a  4k7 resistor). 
This is similar to a BBC B SWR I've got - "32k sideways rom module". Am 
going to document project this some time as I've seen questions a few 
times when browsing back through the list archives.

I found out after an earlier post to the list that  the sideways RAM 
stuff for the model B is in the 1770 DFS
ROM, I've only just figured that out as up until recently the only model 
B I had used the Solidisk DFS!
OTOH I should have guessed as the Master 128 works that way...

OK, now I'm off to re-invent the wheel,

Nick.