Date   : Sun, 31 Aug 2008 01:05:07 +0200
From   : kortink@... (John Kortink)
Subject: FRAM....

On Sat, 30 Aug 2008 21:31:11 +0200, John Kortink wrote:

>[...]
>
>So you're asking for trouble if you don't validate
>nCE with 2MHZE (or, therefore, nOE, which has 2MHZE
>factored in). Without that, it may work some of the
>time, but when the first glitch on nCE comes (and
>there will be many) you're screwed.

The proof of the pudding : validate nCE by adding an
OR gate, inputs phi1 (e.g. IC29 pin 1) and S21 'se',
output S21 'sw'. E.g. by piggy-backing a 74LS32 onto
IC29 (connecting pins 1,7,14) and linking pin 2 and
3 of the new one to S21 'se' and 'sw' respectively.

For argument's sake I just tried this and, hey presto,
FRAM fully working as ordered, and looking stable.

Do note that I tap IC77 pin 8 for my write strobe,
although using the often (ab)used 6502 RnW should
be okay too.


John Kortink

-- 

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