A86: Re: Re: Off/Crash flag


[Prev][Next][Index][Thread]

A86: Re: Re: Off/Crash flag




I don't get this whole checksum thing... what is it?
----- Original Message ----- 
From: Kirk Meyer <kirkmeyer@bigfoot.com>
To: <assembly-86@lists.ticalc.org>
Sent: Wednesday, December 15, 1999 6:30 PM
Subject: A86: Re: Off/Crash flag



There's a wonderful thing called the mailing list archives on ticalc.org.
But since it's my idea, I'll repost it =)

When turned on, the calc checks to RAM page 2 to get a 2-byte _onChecksum.
If it is wrong, then it resets. So, you want to recalc this checksum at the
start of your program and whenever you create/delete/modify a variable if
you want crash protection built into your program. There is a call in the
includes (I forget exactly, search for it in the archives or the include or
something) which will calc this checksum for you. Bravo.

----- Original Message -----
From: Cassady Roop <croop@oregontrail.net>
To: <assembly-86@lists.ticalc.org>
Sent: Tuesday, December 14, 1999 10:21 PM
Subject: A86: Off/Crash flag


>
> A little while back, someone (Clem?) posted info on a flag that tells
> the calc whether it was turned off or if it crashed.  I, being my
> normally dense self, did not save the message.  Could you repost it?
>
> Also, a final note of mine on the argument over whether or not the calc
> is on when it is 'off' (which I think was resolved as it being on), and
> whether or not it (the CPU) is still on even when only the backup
> battery is left...
>
> When I removed the batteries to recharge them, with the calc turned
> 'off' but with Lockdown installed, it cleared the memory when I put them
> back in.  This must mean that the PC was reset to $0000 or wherever its
> default power-up position is.  The calc checked the Off/Crash flag.
> Since the calc was powered down by my program and not the OS, the flag
> was not made to reflect the fact that the calc had indeed been turned
> off, and upon power-up, it thought it had crashed, so it wiped its
> memory clear.  Therefore, since the PC was reset, the CPU must have lost
> power, therefore it was not running.  Of course, everyone was pretty
> sure of that by now anyway, but I just though I would add my additional
> 2.356 cents worth.
>
> Cassady Roop
>







Follow-Ups: References: