Date   : Thu, 28 Aug 2008 17:32:23 +0100
From   : dominic@... (Dominic Beesley)
Subject: FRAM....

Hiya,

Have you tried adding a pull-up resistor to /CE as suggested in the
data-sheet? 

Please keep us informed as to how you get on. I'd love to upgrade some of my
machines to these chips, I do get so tired of having to reload my
non-battery-backed SRAMS ;)

Dom

-----Original Message-----
From: bbc-micro-bounces+dominic=brahms.demon.co.uk@...
[mailto:bbc-micro-bounces+dominic=brahms.demon.co.uk@...] On
Behalf Of Mark Haysman
Sent: 27 August 2008 22:46
To: bbc-micro@...
Subject: [BBC-Micro] FRAM....

Hi Folks.

I've been playing with some FRAM, namely the Ramtron FM1808. I've got a B 
which runs fine with the 62256 SWR mod in socket 15, however, it plays up 
when I pop a FRAM in there.

If I write a ROM to it and reset the machine, it crashes. I initially 
thought that it's the way the FRAM latches addresses on the /CE pin maybe 
that's causing it not to write correctly, but it appears not. I've wired a 
switch to /OE so I can recover the machine when it hangs.

I can write data into it with *SRWRITE or my own loader software, and read 
the data back out and it's identical. I can do an SWR RAM test on it, and it

passes perfectly. I've even tried storing basic & MC programs in it, and 
they load back perfectly and identical, but if I write a ROM in it, nothing,

just a crash with the cursor in the top left corner. This is with ROMs that 
run perfectly if I use a regular 62256 in the same socket. I've even 
confirmed that it's not getting corrupted by resets or power-on, as any data

I write into it is still there perfectly after several power on/off 
sequences.

Any ideas?

Thx, Mark. 



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