Main Area and Open Discussion > General Software Discussion

some basic questions about IT science

(1/2) > >>

kalos:
hello I have some questions about basic IT science

1) I know that the K before a metric unit means x1,000 (eg kcal means kilo calories, which is 1,000 calories), but why 1KB is 1,024 bytes and not 1,000 bytes?

2) since 1KB is 1,024 bytes, 1Kb in how many bits is equivalent to? 1,024 bits or 1,000 bits or something else?

3) a character (letter or digit) stored, is 1 bit or 1 byte?

4) I read "Some sources define a kilobit to mean 1,024 (that is, 210) bits", what the part "(that is, 210)" mean actually? I mean, how they come up with 210???

5) since data is stored in clusters (of magnetic media), why there are bad sectors? I mean, how does a whole sector go bad and not just a cluster?

6) why the common area of a track and TWO sectors is called cluster, but there is no definition for the common area of a track and ONE sector, which is smaller area and thus it is more accurate be used as a unit or area?

7) when do we choose to use bit and when byte (as metric units)? in which occasions?

8) what type of information can registers of CPU hold? what kind of functions can ALU of CPU perform?

thanks!

rsatrioadi:
1) because with electronics it's always powers of two. 1KB = 2^10B = 1024B.
2) 1024b.
3) byte. a bit can only contain 0 or 1.
4) I'm sure it's meant to be 2^10.

f0dder:
2) the 1024-bit "computer kilo" is only really unambiguous when combined with bytes. When applied to bits, some people mean SI-kilo and other 1024-kilo, which is a bit messy. At least it doesn't look as ugly as the KiBiBytes etc. that the lunix zealots want to impose on the world.

3) depends. An ASCII character is defined as one byte, where a byte is usually (but not always!) 8 bits. For a lot of languages, this is not enough, though, and then you have to use a MBCS encoding (which can be unicode or "something else"). Unicode covers several different encodings, btw, and isn't just "two bytes per char".

5) sectors are imposed by the storage device, clusters by the filesystem. Since the storage device addresses in sectors, that's why sectors go bad, and not clusters. A filesystem based on clusters will probably choose to mark the whole cluster bad, though. Not all FSes are cluster-based.

6) again, cluster size is defined by filesystems, not anything else.

7) when dealing with computers - and they aren't metric units (you probably mean Système Internationale, btw?)

8) depends on the CPU, really. x86 CPUs have a number of general-purpose registers (amount and size depending on whether you have a 32- or 64-bit x86 CPU, and the operating mode it's in), a number of floating point registers (or rather, a stack), and a number of multimedia/SIMD registers (also depending on how new the CPU is). Operations available also depends on the type of registers (GP, float, SIMD).

fenixproductions:
2kalos
Little overkill for #1-4:
http://en.wikipedia.org/wiki/Binary_prefix

kalos:
thanks for your replies

why letter a is 01000001? why a letter or generaly character is represented by 8 bits?
since I suppose the total number of possible characters is less than 99,999,999, so why not representing letters/characters as 4 bits, or 6 bits, etc

Navigation

[0] Message Index

[#] Next page