Question

For the 8-bit word 00111001, the check bits stored with it would be 0111. suppose when the word is read from memory, the check bits are calculated to be 1101. what is the data word that was read from memory?

Answer 1

Answer:

No from2-5

Explanation:

Answer 2

00011001  is the data word that was read from memory.

• 8-bit word = 00111001, Check bits stored = 0111.
• There are four bits and it’s position will be
• 20 = 1 ⇒ p₁ = 1
• 21 = 2 ⇒ p₂ = 1
• 22 = 4 ⇒ p₄ = 1
• 23 = 8 ⇒ p₈ = 0.

• Encoded string will be:

        d₁₂ = 0; d₁₁ = 0; d₁₀ = 1; d₉ = 1;

        d₈ = p₈ = 1; d₇ = 1; d₆ = 0; d₅ = 0;

        d₄ = p₄ = 1; d₃ = 1; d₂ = p₂ = 1; d₁ = p₁ = 1.

• ⇒ d₁₂ = 0; d₁₁ = 0; d₁₀ = 1; d₉ = 1;

            d₈ = 1; d₇ = 1; d₆ = 0; d₅ = 0;

            d₄ = 1; d₃ = 1;  d₂ = 1; d₁ = 1.

• Check bits at other end = 1101.

• XOR(0111, 1101) = 1010. 10th bit will change.

• So, new encoded string will be:

        d₁₂ = 0; d₁₁ = 0; d₁₀ = 0; d₉ = 1;

        d₈ = 1; d₇ = 1; d₆ = 0 ; d₅ = 0;

        d₄ = 1; d₃ = 1; d₂ = 1; d₁ = 1.

• Hence the data word that was read from memory will be 00011001.