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6r6_Nostalgia
Account closed
Registered: Oct 2003
Posts: 14 |
Old fucked up c64 models
Anyone experienced games that would not run or crash for no reason on your C64 ?
I have two commodore 64 1984 models, and they both
crash on my disk version of Myth Cartridge.
Recently I got this game tested on someone else's C64
equipment with a oceanic disk drive and the game was running without any problem (both pal and ntsc).
So, I put up my c128d and tested the game there, and,
yes! it was running without any problem from my 1581 and 1571 drive. Tried running the game again on my two c64, and - yes IT WAS CRASHING again.
All my other games are running nicely on these 2 c64, so what is the problem ? I have heard about demos that wouldnt run because of the chips was too hot... So i let
the c64 heat for a few hours, and then tested the game,
crash! still no luck..
Now, I talked to Bamboo on IRC the other day and he
said he experienced similar problems on the game HOOK.
He said something about the scrolling routine would
crash the machine. And he got a 1982 UK model.
AFAIK Myth uses dd04/dd05 to do the scrolling.
We sort of came to a conclusion that certain old c64 models
would fuck up..
Well, any comments.. anyone ?
6R6 - N0stalgia
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raven
Account closed
Registered: Jan 2002
Posts: 137 |
From what i know through discussions
with other coders the problem is a
certain version of the VIC chip (cant
remember exact model).
For some reason it corrupts random
memory locations when $d011 is changed
rapidly.
$d011 is used massivly for FLI and VSP (hardware-
scrolling) which are usually the effects that
cause those C64's to crash.
I suggest you talk with WVL/Xenon. I think he tried
to find some pattern to the corrupted memory
locations, dunno if he succedded :)
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6r6_Nostalgia
Account closed
Registered: Oct 2003
Posts: 14 |
Just tested F4CG, Contex, Censor and Nato's version of
this game on my computer. They all crash after playing
for 30 seconds. |
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Stryyker
Registered: Dec 2001
Posts: 468 |
At one time Graham was doing research into VSP related issues with RAM refresh and so forth. I guess if he knew what needed memory was maybe not getting refreshed properly (I guess VSP can skip some of these cycles) a simple read might refresh them.
C64 RAM can go a little over 1 second before being refreshed? |
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6r6_Nostalgia
Account closed
Registered: Oct 2003
Posts: 14 |
Reading about demo crashes here :
http://groups.google.de/groups?dq=&hl=de&lr=&ie=UTF-8&threadm=P..
.. and runned the following program on my c64:
1000: lda $d011
1003: eor #$20
1005: sta $d011
1008: jmp $1003
After a while (from a few seconds up to several mniutes) the
machine froze...
Fucking Crap!
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6r6_Nostalgia
Account closed
Registered: Oct 2003
Posts: 14 |
oops! start of link here:
http://groups.google.de/groups?dq=&hl=de&lr=&ie=UTF-8&frame=rig.. |
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WVL
Registered: Mar 2002
Posts: 898 |
Well, I never found any patterns :) Also refreshing the RAM by coding it into the routine didn't help shit.. seems to be a bus-problem to me. So the VIC&CPU try to access the memory at the same time, or something like that... Maybe the cpu is even fed data being read by the VIC, so the code that's run is coming from the gfx data, but I don't think this is the case (I tried making the gfx data read only $ea)
Also the memory corruptions occur in every page in the memory, so if $0027 is corrupted, so will $0127, $0227 etc be..
weird. but I couldn't find a way to stop it. |
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raven
Account closed
Registered: Jan 2002
Posts: 137 |
@wvl:
You remember which exact VIC chip version does this?
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algorithm
Registered: May 2002
Posts: 705 |
I had a C64C which had the same problem. Any type of Demo which had Bitmap scrollers (VSP) would sometimes crash on my machine.
The only remedy would be to turn off the machine and turn it back on in the hope that it would work next time
But this problem was finally rectified when I used a new power supply on the same C64C machine. The crashes disappeared!!!!
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WVL
Registered: Mar 2002
Posts: 898 |
@Raven : no, it seems to happen on all VIC's, if you wait long enough. Especially 128's crash very quickly. |
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6r6_Nostalgia
Account closed
Registered: Oct 2003
Posts: 14 |
I dont have a normal power supply... I am using a REU power supply even though I dont have a REU attached... Is that supposed to be unhealthy ?
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