Re: A83: (no subject)
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Re: A83: (no subject)
On 24-Feb-99, Dsc984@aol.com (Dsc984@aol.com) wrote:
>In a message dated 24-02-99 4:01:41 PM Eastern Standard Time,
>lairfight@softhome.net writes:
><< in its simplest form. Sometimes I name the main program prgmSECRET or
> something, and then I include a Pause "DONT PRESS ENTER" before the send9.
> Believe me, you can have lots of fun with this program, but I would
recommend
> knowing how to undo what it does before actually spreading it to people's
> calculators... >>
>What does it do and how do you undo it? I would like to know this BEFORE I
>screw up my calculator.
>-David
Hah.. ok.. =) Let's disassemble the code:
3e1f ld a,1fh
d310 out (10h),a
c9 ret
Port 10h is the lcd driver instruction port. The command 1fh will tell the
lcd to go into test mode. This will show up as some blue lines across the
display, and they won't disappear until you cut the power going to the lcd.
The only way to cut that power is to remove the main batteries for a while &
then put them back in.
If you, like me, have removed your backup battery once and for all, you can
still do this without loosing your memory. Remove the main batteries for
about 20 seconds (don't press on!) and replace them. This will make the
processor reset (including jumping back to 0000h) but will leave the memory
intact.
Linus
\\//
[o][O]
.--> .-------mm--(__)--mm--------.
| Linus Akesson | http://fly.to/linus.world |
`---------------^-- ----- --- -- -- - - - `---------ooO--Ooo----------'
Computers are not intelligent. They only think they are.
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