Post Computer Pictures Here

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > YOSPOS > Post Computer Pictures Here

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NoneMoreNegative: Jul 20, 2000; GOTH FASCISTIC
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shit wizard dad

I'm the guy leaping for joy at hot bullet death

# ? Aug 26, 2016 01:12

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# ? Apr 26, 2024 17:06

Video Nasty: Jun 17, 2003

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# ? Aug 26, 2016 01:18

NoneMoreNegative: Jul 20, 2000; GOTH FASCISTIC
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shit wizard dad

Bill NYSE posted:

.

# ? Aug 26, 2016 01:42

Sagebrush: Feb 26, 2012

DiggityDoink posted:

i had always assumed it was an old virus doing it so these posts about it have been pcool

when that image gets posted people usually conclude it's probably a bit-flip but it's neat to see someone doing the work to verify that

# ? Aug 26, 2016 02:07

Golden-i: Sep 18, 2006; One big, stumpy family

C.H.O.M.E posted:

here is the uncorrupted version:

in vga text mode, you write the text for the frame, then you send that to the vga hardware and the VGA hardware is just gonna look up the glyph for each text character by the ascii code.

the glyphs that I see substituted (and their ascii codes) are

o->g
0x6F->0x67

n->f
0x6E->0x66

N->F
0x4E->0x46

,->$
0x2C->0x24

i->a
0x69-0x61

so you immediately notice that they're all off by 8, that is, they all are a difference of one bit flipping, the bit in position 3 (because 2^3 is 8).
code:
position: 7 6 5 4 _ 3 2 1 0
bit:      0 0 0 0 _ X 0 0 0
so for example
code:
position: 7 6 5 4 _ 3 2 1 0
bit:      0 0 0 0 _ X 0 0 0
n (0x6E): 0 1 1 0 _ 1 1 1 0 
f (0x66): 0 1 1 0 _ 0 1 1 0
so it's an intermittently stuck wire somewhere, could be that the hardware is overheated and causing the timing to screw up and sometimes not flip that position 3 bit to 1 fast enough before it gets latched, or something like that.

Back in my desktop days circa 2004-2007 I had this happen once, but the corruption kept asking us to start Windows in "Cafe Mode".

Once I stopped laughing I eventually figured it down to the video card and probably bad video memory, but I never actually figured out what the cause was, so thanks for this post.

# ? Aug 26, 2016 02:08

Synthbuttrange: May 6, 2007

# ? Aug 26, 2016 02:21

anthonypants: May 6, 2007; by Nyc_Tattoo; Dinosaur Gum

C.H.O.M.E posted:

here is the uncorrupted version:

in vga text mode, you write the text for the frame, then you send that to the vga hardware and the VGA hardware is just gonna look up the glyph for each text character by the ascii code.

the glyphs that I see substituted (and their ascii codes) are

o->g
0x6F->0x67

n->f
0x6E->0x66

N->F
0x4E->0x46

,->$
0x2C->0x24

i->a
0x69-0x61

so you immediately notice that they're all off by 8, that is, they all are a difference of one bit flipping, the bit in position 3 (because 2^3 is 8).
code:
position: 7 6 5 4 _ 3 2 1 0
bit:      0 0 0 0 _ X 0 0 0
so for example
code:
position: 7 6 5 4 _ 3 2 1 0
bit:      0 0 0 0 _ X 0 0 0
n (0x6E): 0 1 1 0 _ 1 1 1 0 
f (0x66): 0 1 1 0 _ 0 1 1 0
so it's an intermittently stuck wire somewhere, could be that the hardware is overheated and causing the timing to screw up and sometimes not flip that position 3 bit to 1 fast enough before it gets latched, or something like that.