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18 answers
678 votes
How are pseudorandom and truly random numbers different and why does it matter?
11 votes

The first random number that I ever used had the excellent property that of any two consecutive random numbers, the second one was larger with a probability of 0.6. Not 0.5. And the third was larger ...

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3 answers
36 votes
What is the difference between screen with resolution 2560*1440 with zoom - 200% and screen with resolution 1280*720?
7 votes

In addition to Kamil's excellent answer (graphics and text will be drawn at the improved resolution and therefore look better), MacOS and iOS actually allow the developer to use different artwork ...

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4 answers
16 votes
Do recommended battery charging practices for a laptop apply to an ultrabook (with non-removable battery)?
4 votes

I don't know how this "everyone" is, but if you remove a battery from any MacBook with a removable battery, then the clock speed will be drastically reduced. The reason is that the charger supplies a ...

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9 answers
195 votes
Why does emptying disk space speed up computers?
2 votes

One effect on spinning drives that I haven't seen mentioned: Access speed and data transfer speed is different on different parts of a disk. A disk rotates at fixed speed. The tracks at the outside ...

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6 answers
28 votes
How do you determine that your hardware is 64 bit capable when there is no operating system installed?
2 votes

If your processor is any non-ancient flavour of x86 processor, you can use the CPUID instruction. On modern processors, you can use it to find out if your CPU is 64 bit capable. On older processors, ...

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7 answers
31 votes
Why do English characters require fewer bytes to represent than other alphabets?
2 votes

If you are interested in how characters are stored, you can go to and look around. At the top of their main page is a link "Code Charts" that shows you all the character codes that are ...

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5 answers
36 votes
Why do different 100% cpu loads cause different temperatures on the cpu?
1 votes

I'll give you an example. Take two loops: for (i = 0; i < 1000000000; ++i) { x += a [i]; } and for (i = 0; i < 1000000000; ++i) { x += a [i]; y += a [i]; z += a [i]; } In the ...

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12 answers
51 votes
Is it wrong to use a laptop with the lid closed?
1 votes

Every MacBook is designed to run with the lid closed. Just attach a monitor, keyboard and mouse. Some people go on eBay and find a very cheap MacBook with broken screen, which makes a very fine ...

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2 answers
-1 votes
How many address lines are needed to access 4 GB RAM?
0 votes

It depends on the processor, and its RAM interface. Some processors will transmit data to and from RAM 128 bits at a time, for example, and individual bytes are sorted out within the processor. 128 ...

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6 answers
8 votes
If IP addresses are unique, why is it so many routers have the address
0 votes

Most IP addresses identify a server or a computer somewhere on the internet. Most, but not all. Some have a special meaning. means "this computer". If my computer sends a message to 127.0....

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17 answers
61 votes
Does an identical cryptographic hash or checksum for two files mean they are identical?
-2 votes

Let's look at this in a practical way. Instead of saying "the hashes are identical" I'll say "I wrote a computer program that calculates the hashes of two files and prints out whether they are the ...

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