[BBC-Micro] Sideways Ram for BBC B

Rick Murray rick at rs432.net
Thu Oct 14 04:23:28 BST 2010

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 

> ......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 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...

More information about the bbc-micro mailing list