Computer Org. & Arch Chap. 2

how many bits long is a double precision number under the IEEE-754 floating point standard?

64 bits (11 bit exponent & 52 bit significand)

what is ASCII and how did it originate?

7 bit code that defines 32 control characters, 10 digits, 52 letters(upper&lower), 32 special characters and space

explain how bit, byte, nibble and word are related

8 bits = 1 byte, 2 nibbles nibble = group of 4 bits word = continuous group of bytes (any size)

name an error detection method that can compensate for burst errors

Reed-Soloman

what is a radix?

a base

what is a biased exponent? what efficiencies can it provide?

shifting the zero mark to represent positive and negative #'s (bias needs to be added)

what is a systematic error detection?

the error bits are appended to the original info byte

why is there always some degree of error in floating point arithmetic when performed by a binary digital computer?

the right bit always gets dropped if more than number of allowed bits, so it can become a larger precision error over time

what is normalization and why is it necessary?

the rule that the first digit of the significand must be 1 , used to minimize the duplication of various relationships in the database

how is the number of redundant bits (check bits) necessary for code related to the number of data bits?

they are added to allow for error detection and/or correction

how many of the "numbers to remember" (in all bases) from figure 2.1 can you remember?

0.25, 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512....

what is a hamming code?

an adaption of the concept of parity, used in situations where random errors are likely to occur, error detection and correction capabilities are increased in proportion to the # of parity bits added to the info word

The word bit is a contraction for what 2 words?

binary digit

why are binary and decimal called positional numbering systems?

each position is weighted by a power of the radix

what is meant by minimum hamming distance?

smallest hamming distance found among all pairs of code words in the code, determines error detecting and correcting capabilities, all pairs of code must have minimum distance of 2

how do cyclic redundancy checks work (CRC)?

systematic error detection scheme, error checking bits are appended to the original info byte, determines whether an error has occurred within a large block of bytes

what is meant by hamming distance and why is it important?

the # of bit positions that 2 code words differ, important for error detection

what is EBCDIC and how is it related to BCD?

the BCD code was limited (6 bit) & didn't have lowercase letters, so EBCDIC is 8 bits & zone digit form

why was unicode created?

to be downloadable with the non Latin alphabet (ASCII and Latin-1 character set), provides code for every written language in the history of civilization

how does overflow in unsigned numbers differ from overflow in signed numbers?

unsigned: not enough bit spaces to fill signed: can get the wrong sign

what is overflow and how can it be detected?

when 2 positive #'s are added and the result is negative (or 2 negative #'s added and result is positive) can be detected by checking the carry in and carry out bit, if they are the same then no error, if different then overflow has occurred

what does overflow mean in the context of unsigned numbers?

when the result of the arithmetic operation is outside the range of allowable precision for the given # of bits

How are complement systems like the odometer on. bicycle?

when you go backwards on a bike, the odometer goes backwards too. you can't know if you went forwards or backwards so you split the # in half and 001-500 represent positive # and 501-999 represent negative #

how many bits does a unicode character require?

16

what is a burst error?

a multiple adjacent bit damage, they're exposed to mishandling and environmental stresses,

what are the 3 component parts of a floating point number

sign bit (1 bit), exponent (5 bits) and significant (8 bits)

name 3 ways in which signed integers can be represented in digital computers and explain the differences

signed magnitude: left most # is the sign (1=neg, 0=pos) and rest of # = magnitude one's complement: switch all 0's and 1's except the sign, if the # is negative, convert it to its complement, "adding the opposite" two's complement: radix complement, one's complement incremented by 1, FLIP BITS AND ADD