Date   : Thu, 14 Oct 2010 05:23:28 +0200
From   : rick@... (Rick Murray)
Subject: Sideways Ram for BBC B

On 13/10/2010 20:14, Mark Haysman wrote:

> As for the 8 SWR board, it's a nice idea, only things I would have designed
> differently is

Sounds quite nice, and it isn't hideously expensive.


> 1) It takes up 2 ROM slots, so you can only have 2 ROMs in a standard
> machine, unless you mod the free sockets for 27256/512s.

Yes, I noticed that - it looks like it has a row of pins on the left and 
right of the board - does it *need* two ROM sockets (ie for addressing 
and such), or is it just designed that way?

Would I be right in thinking I could upload EPROM images into the thing, 
flip the write protect, then it would appear as if I had those ROMs 
installed?


> ......Or, make it take up the length of the 4 slots, and put 2 27512
> compatable slots on the board.

Could be difficult to get anything onto the board in that case...


> 2) Why have the huge AA battery pack for a low power CMOS RAM? I'd have put
> a small coin cell (or rechargable) on the main board.

What's the output of a button cell? The estimation is that the AAs would 
run for about a year.

I'd have been inclined to put a little lithium ion cell on the board 
which trickle-charges when the machine is powered. I'm surprised, unless 
it is an option not mentioned, that there's no charge circuit for using 
rechargeable cells as the AAs.


Best wishes,

Rick.

-- 
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...