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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
ADC bug, CPU fried ?
Hi,
I have this code:
_index .byt 2
LDX #0
CLC
.re LDA _number
ADC #8
STA _number
INX
CPX _index
BNE .re
This should give 24 or not ?
Nomatter where I place the CLC,
it always gives +2
2 times 8 gives me 18
Is my 6510 fried ?
Jan |
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Hoogo
Registered: Jun 2002
Posts: 105 |
_number is not initialized. You add 16 to an unknown value. |
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
ah, this example has no init, but the real code does. :-) |
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hollowman
Registered: Dec 2001
Posts: 474 |
you have a c64 which can load or assemble code and run
it, but it cant add correctly? interesting.. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
The example above should add 16, not 24. But 18 seems weird.... Are you telling us the whole truth here? Is it really initialized, do you have IRQ that destroy A and X etc... And since CPX _index sets C=0 when X<_index it's ok to have the CLC before .re.
And Hollowman has a REALLY good point. |
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
i dont know whats wrong, its so weird.
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WVL
Registered: Mar 2002
Posts: 902 |
bring your machine to x and show us ;) |
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WVL
Registered: Mar 2002
Posts: 902 |
too bad i didn't get to see your machine and see it for myself.
anyway, i can't believe this bug is actually happening.. |
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Perff
Administrator
Posts: 1680 |
@Rambones
Perhaps if you somehow post the machinecode generated by the assembler, we could find an answer? Perhaps the assembler does something strange?
There shouldn't be that many hex-numbers to post for that small code. :)
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Ofcourse it wasn't any HW bug as we all said... :D Rambones and some other dude found out the _SW_ at X and he came to me dead drunk explaining the bug. It was something that wrote garbage in the memory somehow. Anyway.... I could barly hear him since he was absolutly dead drunk. You really have too look for more drunk persons... :D |
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WVL
Registered: Mar 2002
Posts: 902 |
Good ;) that's another 'mystery' solved ;)
it was ofcourse impossible the cpu had problems adding. The whole c64 would never have been able to boot to the basic editor..
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
Hi WVL. yeah :-)
I was trying to convert a char to sprite.
So I get an index for the char like 02, a B.
I add 8, 2 times and get a strange number, because
I forgot to reset and start from 0A00 EVERY time.
I hope this explains it.
Murdock spotted my bug in 3 mins..
Thanks Murdock! |
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dalezy
Registered: Apr 2002
Posts: 476 |
and i spotted your faulty spacebar and a-key! |
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WVL
Registered: Mar 2002
Posts: 902 |
There was nothing wrong with my keys.. guess again why the WOW demo has not been released yet ;) |
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j0x
Registered: Mar 2004
Posts: 215 |
The WOW demo failed for two reasons:
1) A buggy Retro Replay 3.8alpha
2) "somebody" not pressing the spacebar properly
It was a press-space demo, not a hold-space demo :)
Funny, nobody suspected the decimal flag (or the Spanish Inquisition).
j0x/WOW |
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WVL
Registered: Mar 2002
Posts: 902 |
I didn't hold it, i pressed it (hundreds of times ;). It just didn't continue. After a minute i gave up and turned the sound down to ask you guys and suddenly it decided to continue on it's own. weird.
btw, what does the RR have to do with it? :) |
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Bud
Registered: Jan 2002
Posts: 14 |
the Retro Replay 3.8alpha cartridge rom was used when linking the first part of the demo.
That rom sets $9ec5 to $20 which caused the crunched part 3 data in the memory to be corrupted and saved to disk.
This affected the music in the 'interference' part.
This has been fixed now, the demo (Nomen Nescio) can now be found here in the CSDb.
Bud/WOW |
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WVL
Registered: Mar 2002
Posts: 902 |
Ah! I thought he meant the fact that RR3.8 was used on the compo machine! :) |
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Bud
Registered: Jan 2002
Posts: 14 |
Well if that is true then it could have been the problem, as the compo rules (on the X-2004 website) stated that the compo machine would use an Action Replay 6... ;-)
But since the $20 value was in the saved file, it was the RR3.8alpha on our system.
After loading a file with the RR3.8alpha, $9ec5 will be set to $20, i have tested that. |
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
Quote: and i spotted your faulty spacebar and a-key!
That's strange dalezy, because it's actually the right shift key that is faulty. space is not :-) |
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Puterman
Account closed
Registered: Jan 2002
Posts: 188 |
The bug was fixed quite some time ago, but unfortunately there hasn't been another rr release since then... |
