1. Describe the purpose of a buffer and give an example from your own experience

Question

1. Describe the purpose of a buffer and give an example from your own experience where its use clearly benefits system response.
2. Rewrite each of the following arithmetic expressions to take advantage of concurrent processing. Use the terms COBEGIN and COEND to delimit the sections of concurrent code. (see example on page 193)
a.   A + B * R * Z – N * M + C2
b.   (X * (Y * Z * W * R) + M + N + P)
c.   ((J + K * L * M * N) * I)
3. Rewrite each of the following expressions for concurrent processing. Use the terms COBEGIN and COEND to delimit the sections of concurrent code. Identify which expressions, if any, might not run faster in a concurrent processing environment.
a.   H2 * (O* (N + T))
b.   X * (Y * Z * W * R)
c.   M * T * R

Explanation / Answer

1) Buffers are used whenever data is received in sizes that may be different than the ideal size for the hardware or

   software that uses the buffer. For example, a 64-bit processor on a 16-bit bus may have a buffer to hold 16-bit

   requests until they equal 64-bits. Another use of buffers is to keep hardware from getting overwhelmed with

   information. In that scenario, you use a large buffer to hold data until a device or program is ready to receive it,

   instead of just pushing it onto a device that might not be ready. Buffers must be optimized in size to work

    efficiently for the purpose they are designed.

An example from your own experience:

When letters are typed on keybaord in MS DOS program (Like a command prompt), these are line buffered until

carriage return is pressed. The keyboard buffer stores the data temporarily and this data is transferred to the input

output controller when it has a meaning.

This increases the responsiveness of the command prompt. If there is no keyboard buffer, the over all

responsiveness would be decreased. As each letter would be passed to controlller for processing and the control

would revert back to keyboard involving overheads.

2)

a. A + B * R * Z - N * M + C²

COBEGIN

T1 = B*R*Z

T2=N*M

T3 = C*C

COEND

T4=A+T1

T5 = T2+T3

ANS = T4-T5

b. ( X * ( Y * Z * W * R ) + M + N + P )

COBEGIN

T1 = Y*Z

T2 = W*R

T3 = M+N

COEND

COBEGIN

T4 = T1*T2

T5 = P+T3

COEND

T6 = X*T4

ANS = T6+T5

c. ( ( J + K * L * M * N ) * I )

COBEGIN

T1 = K*L

T2 = M*N

COEND

T3 = T1*T2

T4 = J+T3

ANS = T4*I

3) By doing this we can get the result as follows:

[H2 * O], [N + T] => [H2 * O]*[N + T]

[Y * Z], [W * R] => [Y * Z] * [W * R] => [Y * Z * W * R] * X

[M * T], [T * R] => [M * T] * [T * R] => [M * T * T * R] / T

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.