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exercises.md
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@ -202,7 +202,8 @@ Bear in mind the main purpose of this quiz is for you to test your understanding
98. What's the principle of [CPU](cpu.md) [cache](cache.md)? How exactly does it speed up programs? Under what conditions will the cache work well? I.e. how should a program ideally behave to make maximum use of the cache?
99. If you answer "yes" to this question, will you have lied?
100. Form a word by answering each following sentences with one letter. Binary number 1011 in hexadecimal. Base of natural logarithm. *x = min(max(0,t - 1),1)*, *y = 2 - t for 1 <= t <= 2 otherwise t mod 1*, *t* goes from 0 to 3. Number whose square is -1. `'U' - 'T' + 'R'`.
101. Did you enjoy this quiz?
101. In C this `float x = 16777216; printf("%d\n",x == (x + 1));` outputs `1` (or at least it is possible) -- what the fuck. How can a number equal itself plus one? Explain what's going on here.
102. Did you enjoy this quiz?
### Answers
@ -307,7 +308,8 @@ sin(x) / cos(x) - log2(2) = tg(x) - 1*, so we get *tg(x) >= 1*. So that will hol
98. Cache is a small memory placed between the CPU and main memory (RAM), it is a very fast type of memory, faster than the main memory, but it's also much smaller than main memory. The idea is that programs typically do a lot of work in some small region of main memory, they keep reading and writing the same (or nearby) memory cell(s) over and over and only after a while move somewhere else. So once the program starts a work in some memory area, the cache can load that area, let the program do its work very quickly in the cache, and then (when the program moves elsewhere) copy the results back from the cache to the memory. It's similar to downloading a file from the Internet to the disk, then editing the file locally and later on uploading it back. However the cache will be effective only if the assumption we made hold, i.e. if the program really mostly works in small areas of memory and makes minimum of long jumps, so if a program wants to fully utilize the cache, it should try to minimize these long jumps (for example by putting related data close to each other).
99. There is no correct answering with either "yes" or "no" (this is therefore the correct answer). The question can be reworded as: *Is "yes" the wrong answer to this question?*, which can be reworded as: *Is "no" the correct answer to this question?* If we try both possible answers -- "yes" and "no" -- we find neither works.
100. BENIS
101. yes
101. [Floating point](float.md) had decreasing precision towards higher values, this one if already beyond the resolution of 1, so the float type cannot represent this number plus one, adding one rounds the result down to the same number.
102. yes
## Other