Due: 9/18

Be sure your answers are TYPED!!!

1.   Explain each of the following terms in your own words:
     a.    Translator.
     b.    Interpreter.
     c.    Virtual machine.

2.   What is the difference between interpretation and translation?

3.   Consider a computer with identical interpreters at levels 1, 2, and 3. It takes an interpreter n instructions to
     fetch, examine, and execute one instruction. A level 1 instruction takes k nanoseconds to execute. How long
     does it take for an instruction at levels 2, 3, and 4?

4.   Some instructions at the operating system machine level are identical to conventional machine language
     instructions. These instructions are carried out directly by the microprogram rather than by the operating
     system. In light of your answer to the preceding problem, why do you think this is the case?

5.   In what sense are hardware and software equivalent? Not equivalent?

6    A certain computation is highly sequential -- that is, each step depends on the one preceding it. Would an array
     processor or a pipeline processor be more appropriate for this computation? Explain.

7    To compete with the newly invented printing press, a certain medieval monastery decided to mass-produce
     handwritten paperback books by assembling a vast number of scribes in a huge hall. The head monk would then
     call out the first word of the book to be produced and all the scribes would copy it down. Then the head monk
     would call out the second word and all the scribes would copy it down. This process was repeated until the
     entire book had been read aloud and copied. Which of the parallel processor systems of Sec. 2.1.3 does this
     system most resemble?

8.   Which of the following memories are possible? Which are reasonable? Explain.

     a.   10-Bit address, 1024 cells, 8-bit cell size
     b.   10-Bit address, 1024 cells, 12-bit cell size
     c.   9-Bit address, 1024 cells, 10-bit ceil size
     d.   11-Bit address, 1024 cells, 10-bit cell size
     e.   10-Bit address, 10 cells, 1024-bit cell size
     f.   1024-Bit address, to ceils, 10-bit ceil size

9    Sociologists can get three possible answers to a typical survey question such as "Do you believe in the tooth
     fairy?" namely, yes, no, and no opinion. With this in mind, the Sociomagnetic Computer Company has
     decided to build a computer to process survey data. This computer has a binary memory -- that is, each byte
     (byte?) consists of 8 trits, with a trit holding a 0, 1, or 2. How many bits are needed to hold a 6-bit number?
     Give an expression for the number of bits needed to hold n bits.

10.  How long does it take to read a disk with 800 cylinders, each containing five tracks of 32 sectors? First, all the
     sectors of track O are to be read starting at sector 0, then all the sectors of track 1 starting at sector 0, and so
     on. The rotation time is 20 msec, and a seek takes 10 msec between adjacent cylinders and 50 msec for the
     worst case. Switching between tracks of a cylinder can be done instantaneously.

11.  Devise a code for the digits 0 to 9, in binary, whose Hamming distance is 2.

12.  Transmission errors on telephone lines often occur in bursts rather than individually. Because the basic
     Hamming code can only correct single errors within a character, it is of no use if a noise burst garbles n
     consecutive bits. Devise a method of transmitting ASCII text over a line where noise bursts may garble as many
     as 100 consecutive bits. Assume that the minimum interval between two noise bursts is thousands of characters.
     Hint: Think carefully about the order of bit transmission.

13.  The Hi-Fi Modem Company has just designed a new frequency-modulation modem that uses 16 frequencies
     instead of just 2. Each second is divided into n equal time intervals, each of which contains one of the 16
     possible tones. How many bits per second can this modem transmit, using synchronous transmission?

14.  How many characters/sec (7 bits + parity) can be transmitted over a 2400-bps line in each of the following
     modes?

     a.   Synchronous
     b.   Asynchronous (1 start bit and 1 stop bit)

15.  What is the hamming distance for the following set of words?

     010101010101
     010010101101
     101010101010
     101101010010
     101010010010
     010101101101
     101101010010
     010010101010