
Safe VSP – 30 year old Commodore 64 bug demystified (2013) - qmr
http://www.linusakesson.net/scene/safevsp/index.php
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panic
Previously:
[https://news.ycombinator.com/item?id=5314959](https://news.ycombinator.com/item?id=5314959)

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NKCSS
Aswesome :)

"Finally, this phenomenon hinges on the exact timing of the RAS signal at the
nanosecond level, and on many machines the critical situation simply doesn't
occur. The timing (and thus the probability of a crash) depends on factors
such as temperature, VIC revision, parasitic capacitance and resistance of the
traces on the motherboard, power supply ripple and interference with other
parts of the machine such as the phase of the colour carrier with respect to
the dotclock. The latter is assigned randomly at power-on, by the way, which
could be the reason why a power-cycle sometimes helps."

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Malic
Well of _course_ LFT was the one who discovered the reason! His work is
impressive. Example:
[http://www.linusakesson.net/scene/craft/index.php](http://www.linusakesson.net/scene/craft/index.php)

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matt_d
Reminded me a bit about the modern DRAM issue, i.e., row hammer -- although
the details are of course different --
[https://en.wikipedia.org/wiki/Row_hammer](https://en.wikipedia.org/wiki/Row_hammer)

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jrowley
Slightly off topic but it's pretty cool to live in a day and age where people
can post logic analyzer dumps of hardware processes and debug them together on
the internet.

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tdaltonc
As a neuroscientist, this makes me feel better about this:

[https://news.ycombinator.com/item?id=11843376](https://news.ycombinator.com/item?id=11843376)

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nekopa
Shit like this is where I wish we could have a demo scene for modern
architecture. (Maybe there is one, and I'm just don't know about it)

I have always fantasized about going back to the bad old days, where you have
to boot the computer into the program you want to run.

I dream about having the full capability of modern computing to just run one
program. Without any overhead. Without an OS.

~~~
qmr
Nothing is preventing you from doing that.

~~~
newobj
[https://en.wikipedia.org/wiki/Unified_Extensible_Firmware_In...](https://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface#Secure_boot)

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yuhong
It is unfortunate 4164s dates before CAS before RAS refresh. Not all 41256s
supports it either I think. There were even SIMMs with labels indicating that
they are for Mac Plus/SE only when Apple had to use Siemens chips that don't
support it.

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wolfgke
One should add '[2013]'.

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qmr
Bias for newness is a bad thing.

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corndoge
Having read this several years ago, I think [2013] is appropriate.

~~~
wolfgke
If you scroll to the bottom of
[http://www.linusakesson.net/scene/safevsp/index.php](http://www.linusakesson.net/scene/safevsp/index.php)
you can read "Posted Wednesday 20-Mar-2013 23:23". :-)

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MOARDONGZPLZ
Not the point. The point is to have it in the title so everyone knows BEFORE
clicking.

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arviewer
He should have waited ten more years, then it would have been a 40 year old
bug. Much more impressive! ;-P

~~~
ethbro
Depends on how much oak you like in your bug.

