A device has been used in cycle stealing mode of DMA. A word of 4 bytes can be…
2021
A device has been used in cycle stealing mode of DMA. A word of 4 bytes can be transferred when it is available. The memory cycle time is 40 ms and CPU is idle for 10% of its time. What is the data transfer rate of the device?
- A.
1011 bits/sec
- B.
11.11 B/sec
- C.
12.33 B/sec
- D.
2048 B/sec
- E.
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Correct answer: B
Step 1: Calculate the number of memory cycles per second. Memory cycle time is 40 ms, so:
Number of cycles per second = 1 / 0.04 = 25 cycles/sec.
Step 2: The CPU is idle for 10% of its time, so DMA can use 10% of the memory cycles:
DMA cycles per second = 25 × 0.1 = 2.5 cycles/sec.
Step 3: Each transfer is 4 bytes (32 bits), so the data transfer rate is:
Data transfer rate = 2.5 × 4 = 10 B/sec.
Thus, the data transfer rate of the device is 10 B/sec.
हिन्दी उत्तर:
चरण 1: स्मृति चक्र समय 40 मिलीसेकंड है, इसलिए प्रति सेकंड चक्रों की संख्या = 1 / 0.04 = 25।
चरण 2: CPU 10% समय खाली रहता है, इसलिए DMA 10% चक्रों का उपयोग कर सकता है: DMA चक्र प्रति सेकंड = 25 × 0.1 = 2.5।
चरण 3: प्रत्येक स्थानांतरण 4 बाइट्स है, इसलिए डेटा स्थानांतरण दर = 2.5 × 4 = 10 बाइट्स/सेकंड।
इसलिए, डिवाइस की डेटा स्थानांतरण दर 10 बाइट्स/सेकंड है।