Date   : Sat, 17 Oct 2009 12:45:36 +0200
From   : kortink@... (John Kortink)
Subject: ROM upgrades on the cheap

On Sat, 17 Oct 2009 02:00:47 +0200, Rick Murray <rick@...>
wrote:

>John Kortink wrote:
>
>> It's not complicated, and there's more than one way.
>> Mine (which I'm actually using in my 'work' Beeb) is
>> this :
>> http://web.inter.nl.net/users/J.Kortink/rewire.txt
>
>Reading that now.
>
>I do have one question - the top says "If you rewire all 4 of your 
>sideways ROM sockets, you will be able to load and subsequently use 8 
>different sideways ROM images at the same time."
>
>Sounds pretty flexible, certainly for developing EPROM images. But, um, 
>if you rewire all four sockets to be SRAM, and the fifth holds the 
>MOS... how will you be able to load anything INTO the sideways ROM?

With difficulty. But that's a practical problem, not
a technical one.

One thing that comes to mind, since a write line is now
available from the socket, is making a little header PCB
with a flash ROM on top (e.g. a 29C256). Put any (semi-)
permanent code into that. Unfortunately there are no flash
ROMs with standard SRAM pinout.

>Surely you'd need to make do with only six and have the other slot 
>containing DNFS or whatever, plus any EPROM that has some code to do the 
>*SLOAD?
>
>
>Right. Bookmarked that.
>
>
>Aaaargh! I remember that digitiser! God, I almost fell over dead seeing 
>a design for an Acorn podule in Elektor. I might even have the pages 
>around here someplace on the off chance I'd ever get around to building it.

I even have some leftover PCBs ...


John Kortink

-- 

Email    : kortink@...         
Homepage : http://www.inter.nl.net/users/J.Kortink

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