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fullmetalcoder


Member


Joined: 01 Aug 2009
Posts: 139
Posted: 08 Aug 2009 09:11:42 am    Post subject:
the is program uses the extra RAM pages (83+SE, 84+ and 84+SE actually have 128kb of RAM) to store data instead of occupying the pages used by the OS. the advantage of that is that it extends the storage capacity and should theoretically allow faster I/O than ROM. The disavantage is that this cannot be accessed directly by any part of the OS whatsoever (including Basic programs) and that it will disappear upon RAM clear.
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calc84maniac


Elite


Joined: 22 Jan 2007
Posts: 770
Posted: 08 Aug 2009 09:30:29 am    Post subject:
fullmetalcoder wrote:
the is program uses the extra RAM pages (83+SE, 84+ and 84+SE actually have 128kb of RAM) to store data instead of occupying the pages used by the OS. the advantage of that is that it extends the storage capacity and should theoretically allow faster I/O than ROM. The disavantage is that this cannot be accessed directly by any part of the OS whatsoever (including Basic programs) and that it will disappear upon RAM clear.

It doesn't disappear upon RAM clear... (this is how Omnicalc RAM Restore works)
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Igrek


Member


Joined: 23 Aug 2007
Posts: 151
Posted: 08 Aug 2009 09:59:49 am    Post subject:
Well there is actually (nearly) no advantage over using the archive. But you're right I shouldn't call both the program and the extra ram pages it uses 'xram'. In fact this program just increases the storage space on the calculator by 96 kilobytes, that's all.
Edit: I probably haven't refreshed this page for too long.

Last edited by Guest on 08 Aug 2009 10:01:02 am; edited 1 time in total
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fullmetalcoder


Member


Joined: 01 Aug 2009
Posts: 139
Posted: 08 Aug 2009 10:50:31 am    Post subject:
calc84maniac wrote:
It doesn't disappear upon RAM clear... (this is how Omnicalc RAM Restore works)

Depend what RAM clear you consider : software (done by the OS in certain cases by filling 8000-FFFF with zeros) or hardware when the batteries run-out (including the backup one of course). RAM needs power to keep its content, flash doesn't.

As for advantage over archive I think there are at least two : avoid garbage collection/defrag and avoid overusing the flash (it has a smaller lifetime than RAM). I have not made any measurement so I can't tell there is any actual performance penalty using flash, except the delay required to unlock/lock flash (page swapping probably as the same cost regardless of the memory swapped in/out a bank).
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Igrek


Member


Joined: 23 Aug 2007
Posts: 151
Posted: 08 Aug 2009 10:52:58 am    Post subject:
I hope I have fixed it now, pheww...
[attachment=2738:XRAM.8xp]

Last edited by Guest on 08 Aug 2009 10:54:22 am; edited 1 time in total
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