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Old 2004-06-18, 20:56   #1
JuanTutors
 
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Mar 2004

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Default Resuming test every 65536 iterations

Prime95 is resuming its LL test every 65536 iterations. It doesn't say why, and it doesn't say that it's stopping and restarting. I just have it running 24/7 without any special restrictions placed in prime.ini. My disk is not full or anything like that. Does this happen to anyone else? Do you know why this is happening?
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Old 2004-06-18, 22:39   #2
clowns789
 
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I noticed in Gameshark the max number for a value was 65535, and it explained why. That number must somehow be important in computers.
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Old 2004-06-18, 23:53   #3
PrimeCruncher
 
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I've never heard of that behavior before, but 65536 is special because it is the largest value that will fit inside a word value or register (16 bits, IIRC).
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Old 2004-06-19, 02:02   #4
Xyzzy
 
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Without trying I've memorized:

2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576 & 2097152

Most of those numbers happen to coincide with the memory checker in the BIOS in the long line of computers I have owned... I guess watching my computer boot all these years has paid off...

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Old 2004-06-19, 02:51   #5
ColdFury
 
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Quote:
Originally Posted by PrimeCruncher
I've never heard of that behavior before, but 65536 is special because it is the largest value that will fit inside a word value or register (16 bits, IIRC).
With most computers it's 32 or 64 bits.
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Old 2004-06-20, 13:56   #6
Danath
 
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65536 is equal to 64 x 1024. That means that 64 Kbytes are equal to 65536 bytes, or that 64 Mbytes are equal to 65536 Kbytes (so if your computer has 64 Mb of RAM, you should see this magic number every day - at the computer's startup ).

Those who were programming for real-mode DOS environment once should be able to say more about this number - the maximal size of one segment of memory was 64 Kb (or 65536 bytes), so a program module's size couldn't exceed that value.

ColdFury, in programming terms, a "byte" has 8 bits (and can take 2^8 = 256 different values), a "word" has two bytes and therefore has 16 bits (and can take 2^16 = 256^2 = 65536 different values). Of course, modern processors have 32 or 64 bit registers (what means that the largest value a register can hold is 32 or 64 bit in size), but some general-purpose registers can be "divided" into several smaller "subregisters", including a word register (16 bit) that PrimeCruncher mentioned.

Xizzy, all the numbers you've mentioned are of 2^n form, and represent the usual sizes of computers' RAM. But I sense that these numbers are somehow connected with GIMPS (does anybody here know how?) .
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Old 2004-06-21, 01:00   #7
rbarreira
 
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Quote:
Originally Posted by PrimeCruncher
I've never heard of that behavior before, but 65536 is special because it is the largest value that will fit inside a word value or register (16 bits, IIRC).
65536 is the number of different values that you can represent with a word value, but if you assume that numbers start at 0, the largest number you can represent with those values is 65535 :)
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Old 2004-06-21, 01:11   #8
ColdFury
 
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Quote:
ColdFury, in programming terms, a "byte" has 8 bits (and can take 2^8 = 256 different values), a "word" has two bytes and therefore has 16 bits (and can take 2^16 = 256^2 = 65536 different values). Of course, modern processors have 32 or 64 bit registers (what means that the largest value a register can hold is 32 or 64 bit in size), but some general-purpose registers can be "divided" into several smaller "subregisters", including a word register (16 bit) that PrimeCruncher mentioned.
I know what a byte and a word is. I've been programming for 12 years. The word size of an architecture varies. The ability to split the registers into smaller sizes is rare in RISC architectures. The reason why the x86 architecture has so many different register sizes is to maintain backwards compatibility with old ISA versions.
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