Questions and Answers of Computer Architecture

Discuss the similarities and differences between memory management fragmentation and disk fragmentation.
Nearly every operating system separates the file system from the I/O services. What is the advantage in doing so?
What is the difference between the logical description of a file and the physical description?
An operating system is described as an event-driven program. What is meant by event driven? Explain how the dispatching operation fits this description.
Describe the two methods that are used to provide concurrent operation of multiple processes on a single CPU. What are the advantages of each method? What is the advantage of providing concurrent
You are probably familiar with the standard Windows interface. Suppose you could replace the Windows shell with a different interface shell. What might be the advantages and disadvantages of
What are the limitations of providing a BIOS in ROM?
Concurrency, of course, is a requirement for modern operating systems. What are the major challenges that an OS designer faces in supporting efficient concurrency that she would not face if the
For each of the most popular commands in Windows (or Linux if you prefer), identify the type of operating system service that is being provided, and identify the basic module or modules that are
What are the specific limitations of a computer system that provides no operating system? What must be done to load and execute programs?
a. What is the binary sequence represented by the 4B/5B encoded sequence11110011111101111110?b. What is the binary sequence represented by the 4B/5B encoded sequence10101010101010101011?
The Little Prince Computer (LPC) is a mutant variation on the LMC. (The LPC is so named because the differences are a royal pain.) The LPC has one additional instruction. The extra instruction
a. Consider a CPU with two parallel integer execution units. An addition instruction requires 2 clock pulses to complete execution, and a multiplication requires 15 clock pulses. Now assume the
Write a program in your favorite language that will convert all ASCII uppercase and lowercase letters to EBCDIC code. For an additional challenge, also convert the punctuation symbols, indicating
Approximately how many pages of pure 16-bit Unicode text can a 650MB CD-ROM hold?
What are the 16-bit 1’s and 2’s complements of the following binary numbers?a. 10000b. 100111100001001c. 0100111000100100
Add the following 16’s complement hexadecimal numbers 4F09D3A5Is your result positive or negative? How do you know? Convert each number to binary and add the binary numbers. Convert the
In the Pink-Lemon-8 computer, real numbers are stored in the formatSEEM M M M8where all the digits, including the exponent, are in octal. The exponent is stored excess-408. The mantissa is stored as
a. Convert the decimal number 19557 to floating point. Use the format SEEMMMM. All digits are decimal. The exponent is stored excess-40 (not excess-50). The implied decimal point is at the beginning
a. Convert the number 123.57 × 1015 to the format SEEM M M M, with the exponent stored excess-49. The implied decimal point is to the right of the first mantissa digit.b. What is the smallest number
Real numbers in the R4–D4 computer are stored in the formatSEEM M M M M4where all the digits, including the exponent, are in base 4. The mantissa is stored as sign and magnitude, where the sign is
Convert the following binary and hexadecimal numbers to floating point format. Assume a binary format consisting of a sign bit (negative = 1), a base 2, 8-bit, excess-128 exponent, and 23 bits of
Represent the decimal number 171.625 in 32-bit IEEE 754 format.
Show the packed decimal format for the decimal number − 129975.
The following decimal numbers are stored in excess-50 floating point format, with the decimal point to the left of the first mantissa digit. Add them. A 9 is used as a negative sign. Present your
Using the same format found in Exercise 5.19, add and multiply the following floating point numbers. Present your answers in both floating point and sign-and-magnitude
What are the criteria that define a von Neumann architecture? How does the example in this chapter in which we enter and add two numbers illustrate each of the criteria?
Consider the example in this chapter in which we enter and add two numbers. Suppose we had stored the first input entry in mailbox location 00. Would the program have produced the same result? What
Write a Little Man program that accepts three values as input and produces the largest of the three as output.
Write a Little Man program to accept an indefinite number of input values. The output value will be the largest of the input values. You should use the value 0 as a flag to indicate the end of input.
Write a Little Man program that accepts three values as input and outputs them in order of size, largest to smallest.
Write a Little Man program that adds a column of input values and produces the sum as output. The first input value will contain the number of values that follow as input to be added.
Write a Little Man program that prints out the odd numbers from 1 to 99. No input is required.
Write a Little Man program that prints out the sums of the odd values from 1 to 39. The output will consist of 1, 1 + 3, 1 + 3 + 5, 1 + 3 + 5 + 7 . . . . No input is required. As an aside, do you
The following Little Man program is supposed to add two input numbers, subtract a third input number from the sum, and output the result, i.e.,OUT = IN1 + IN2 ˆ’ IN3What is wrong with this
Suppose we have a need to handle both negative and positive data beyond the simple test in the various conditional branch instructions. One way to do this would be to replace the subtract instruction
Consider a more realistic alternative:Suppose a small program is permanently stored in the last few mailbox locations. A BRANCH instruction at location 00, also permanent, will start this program.
Show carefully how you would implement an IF-ELSE statement using Little Man instructions.
Show how you would implement a DO-WHILE statement using Little Man instructions.
The input data values in our problems have always been entered in the order that they were to be used. This is not always possible or convenient. Can you think of a simple way to accept input data in
Suppose the Little Man Computer had been implemented as a 16-bit binary machine. Assume that the binary LMC provides the same instruction set, with the same op codes (in binary, of course), and the
The original version of the Little Man Computer used op code 7 (i.e., instruction 700) for a COFFEE BREAK instruction instead of op code 0. What is the advantage of using 000 for the COB instruction
When we discussed conditional branching we claimed that a BRANCH NEGATIVE instruction is not necessary. Show a sequence of BRANCH instructions that will cause a program to branch to location 50 if
Show a sequence of instructions that will cause a program to branch to location 75 if the value in the calculator is greater than zero.
Suppose that the following instructions are found at the given locations in memory:a. Show the contents of the IR, the PC, the MAR, the MDR, and A at the conclusion of instruction 20.b. Show the
One large modern computer has a 48-bit memory address register. How much memory can this computer address?
Why are there two different registers (MAR and MDR) associated with memory? What are the equivalents in the Little Man Computer?
Show the steps of the CPU fetch–execute cycle for the remaining instructions in the Little Man instruction set.
Most of the registers in the machine have two-way copy capability; that is, you can copy to them from another register, and you can copy from them to another register. The MAR, on the other hand, is
a. What is the effect of shifting an unsigned number in a register 2 bits to the left? 1 bit to the right? Assume that 0s are inserted to replace bit locations at the end of the register that have
If you were building a computer to be used in outer space, would you be likely to use some form of flash memory or RAM as main memory? Why?
Many older computers used an alternative to the BRANCH ON CONDITION instruction called SKIP ON CONDITION that worked as follows: if the condition were true, the computer would skip the following
Suppose that the instruction format for a modified Little Man Computer requires two consecutive locations for each instruction. The high-order digits of the instruction are located in the first mail
As computer words get larger and larger, there is a law of diminishing returns: the speed of execution of real application programs does not increase and may, in fact, decrease. Why do you suppose
Most modern computers provide a large number of general-purpose registers and very few memory access instructions. Most instructions use these registers to hold data instead of memory. What are the
Create the fetch–execute cycle for an instruction that moves a value from general purpose register-1 to general-purpose register-2. Compare this cycle to the cycle for a LOAD instruction. What is
What are the trade-offs in using a serial bus versus a parallel bus to move data from one place to another?
Until recently, most personal computers used a parallel PCI bus as a back plane to interconnect the various components within the computer, but the PCI bus was rarely, if ever, used to connect
Explain why skew is not a factor in a serial bus.
Point-to-point buses generally omit lines for addressing. Why is this possible? Suppose a point-to-point bus is used to connect two components together where one of the components actually represents
Find a good reference that describes the x86 chip. Discuss the features of the architecture that make super scalar processing possible in this chip. What limitations does the Pentium architecture
Suppose that a CPU always executes the two instructions following a branch instruction, regardless of whether the branch is taken or not. Explain how this can eliminate most of the delay resulting
Some systems use a branch prediction method known as static branch prediction, so called because the prediction is made on the basis of the instruction, without regard to history. One possible
How would you modify the Little Man Computer to implement the pipe lined instruction fetch–execution unit model that was described in this chapter? What would it take to supply multiple execution
a. Suppose we are trying to determine the speed of a computer that executes the Little Man instruction set. The LOAD and STORE instructions each make up about 25% of the instructions in a typical
The goal of scalar processing is to produce, on average, the execution of one instruction per clock tick. If the clock ticks at a rate of 2 GHz, how many instructions per second can this computer
Consider a cache memory that provides three hundred 16-byte blocks. Now consider that you are processing all the data in a two-dimensional array of, say, four hundred rows by four hundred columns,
Carefully discuss what happens when a cache miss occurs. Does this result in a major slowdown in execution of the instruction? If so, why?
What is the purpose of the tag in a cache memory system?
Describe the trade-offs between the memory cache write-through and write-back techniques.
Carefully describe the advantages and disadvantages of master–slave multiprocessing and symmetrical multiprocessing. Which would you select for fault-tolerant computing? Why?
Locate information about the Cell Processor. Describe the tasks performed by the various slave processors. What is the primary role of the master processor? Explain the advantages of master–slave
As you know, a single CPU processes one instruction at a time. Adding a second CPU (or core, in current terminology) allows the system to process two instructions at a time, simultaneously,
Why would DMA be useless if the computer did not have interrupt capability?
What is the advantage of using a disk controller to control the hard disk? How else could you do the job that the disk controller does?
DMA is rarely used with dumb computer terminals. Why?
Consider the interrupt that occurs at the completion of a disk transfer.a. “Who” is interrupting “whom”?b. Why is the interrupt used in this case? What would be necessary if there were no
Suppose you wish to send a block of data to a tape drive for storage using DMA. What information must be sent to the tape controller before the DMA transfer can take place?
What is polling used for? What are the disadvantages of polling? What is a better way to perform the same job?
To use a computer for multimedia (moving video and sound), it is important to maximize the efficiency of the I/O. Assume that the blocks of a movie are stored consecutively on a CD-ROM. Describe the
Consider the interface between a computer and a printer. For a typical printout, it is clearly impractical to send output data to the printer one byte or one word at a time (especially over a
The UNIX operating system differentiates between block-oriented and character oriented devices. Give an example of each, explain the differences between them, and explain how the I/O process differs
Describe a circumstance where an interrupt occurs at the beginning of an event. Describe a circumstance where an interrupt occurs at the completion of an event. What is the difference between the
In general, what purpose does an interrupt serve? Stated another way, suppose there were no interrupts provided in a computer. What capabilities would be lost?
What is the difference between polling and polled interrupt processing?
Describe the steps that occur when a system receives multiple interrupts.
Explain why it is easy to perform read and write in place on a disk but not on a tape.
What are the advantages of flash memory over hard disk storage? What are the advantages of hard disk over flash memory storage? What are the advantages of both hard disk and flash memory storage over
A multiplattered hard disk is divided into 1100 sectors and 40,000 cylinders. There are six platter surfaces. Each block holds 512 bytes. The disk is rotating at a rate of 4800 rpm. The disk has an
For a motion picture image it may be necessary to change every pixel in the image as many as thirty times per second, although usually the amount of change is somewhat smaller. This means that
Find a current computer ad in a magazine or newspaper or online. Identify each of the featured items in the ad, show its position in the system block diagram of Figure 11.1, explain how it operates,
Cloud computing is a recent technology being marketed and used as a means to provide off-site computing power to an organization. Locate information about cloud computing and compare cloud computing
Many phone companies are replacing the wire in their phone systems with fiber-optic cable. What do they expect to gain from doing so?
In recent years, much of the storage and communication of data has been in digital form, even if the source data is actually analog. Even most television is now transmitted digitally. What benefits
Consider a communication system that converts a digital signal to analog form for transmission, then recovers the digital signal at the receiving end. Another system starts with an analog signal,
Discuss the trade-offs between coaxial wire and fiber-optics in a network made up of fifty computer stations all located within 1000 feet of each other.
What effect does time-division multiplexing have on the bandwidth requirements of a channel?
Describe the advantages that repeaters have over amplifiers.
Discuss the trade-offs between fiber-optic and satellite communication in terms of costs, signal capacity, signaling method, interference, likelihood of failure and repair issues, multi-point
What effect would you expect a wider bandwidth to have on the noise in a channel?

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