# TCS Placement: Sample Questions 93 - 95 of 502

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## Question 93

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### Write in Short

If A is travelling at 72 km per hour on a highway. B is travelling at a speed of 25 meters per second on a highway. What is the difference in their speeds in m/sec.

### Explanation

• Speed of A =
• Converting the speed of A in m/sec,
• Speed of B =
• Taking the difference of speed, speed of B - speed of A =
• The difference between A and B is .

## Question 94

### Question

MCQ▾

Satish earns 240 weekly. 12 % of big amount + earning weekly = 540, what is the big amount?

Choice (4)

a.

3200

b.

1000

c.

2500

d.

3600

c.

### Explanation

Let big amount be ₹ x.

Satish earns ₹ 240 weekly.

We are given, 12 % of big amount + earning weekly = 540

So, big amount is ₹ 2500.

## Question 95

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### Describe in Detail

Essay▾

What is cycle stealing?

### Explanation

• We encounter cycle stealing in the context of Direct Memory Access (DMA) .
• Either the DMA controller can use the data bus when the CPU does not need it, or it may force the CPU to temporarily suspend operation- this is technique is called cycle stealing.
• That cycle stealing can be done only at specific break points in an instruction cycle.
• Cycle stealing is a method of accessing computer memory (RAM) or bus without interfering with the CPU.
• It is similar to direct memory access (DMA) for allowing I/O controllers to read or write RAM without CPU intervention.
• Clever exploitation of specific CPU or bus timings can permit the CPU to run at full speed without any delay if external devices access memory not actively participating in the CPU՚s current activity and complete the operations before any possible CPU conflict.
• Requests by DMA devices for using the bus are always given higher priority than processor requests.
• Among different DMA devices, top priority is given to high-speed peripherals.
• Since the processor originates most memory access cycles, it is often stated that DMA steals memory cycles from the processor.
• If DMA controller is given exclusive access to the main memory to transfer a block of data without interruption, this is called block or burst mode.

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