Date   : Fri, 25 Jul 2008 02:00:29 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: EEPROM writing in SW rom bank?

Charlie.Robson@... wrote:
> I'm trying to write an EEPROM by connecting a flying lead from the /WE
> line as one would for a RAM chip. Needless to say it's not working for
 
IC77p8 is the ususal write strobe collection point. I though I'd
documented it at <http://mdfs.net/Info/Comp/BBC/SROMs>, but I've
only done it for 32K devices.
 
Somebody mentioned flash. I seem to remember that EEPROMs need to
be written in a cycle, which I think is similar to flash, using
code something like:
 
LDA (src),Y
.lp
STA (dst),Y  :\ Write byte
CMP (dst),Y
BNE lp       :\ Keep writing until read byte matches
STA (dst),Y
STA (dst),Y  :\ Twice more for luck
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
Youth has now fled. Their best years have been passed in the service
of the party. They are ageing and their ideals have also passed,
dispersed by the contrarities of daily struggles.