Chapter 5 Processor fundamentals Flashcards

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1
Q

What are the basic features of the Von Neumann model of a computer?

A
  • There is a processor, a central processing unit.
  • The processor has direct access to a memory
  • The memory contains a stored program that is being executed.
  • The stored program consists of individual instructions
  • The processor executes instructions sequentially
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2
Q

Which are the main components of a CPU and what do they do?

A
  • The ALU is the Arithmetic and logic circuit and it is responsible for any arithmetic or logic processing that might be needed when a program is running.
  • The control unit that does the following:
    • Controls the flow of data through the processor and computer
    • Ensures that computer data is handled correctly
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3
Q

Which are the two most important parts of the control unit and why?

A

The internal clock - controls the cycles inside the processor and its frequency is called clock speed
The system clock - controls the activities outside the processor

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4
Q

What are registers, where are they situated and how much can they store?

A

The registers are storage components very close to the ALU and can store 16, 32 or 64 bits.

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5
Q

What are the general purpose registers?

A

A general purpose register or an accumulator can store only a single value at a given time.

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6
Q

What is an accumulator?

A

An accumulator is a general purpose register that stores a value or instruction before and after the execution of an instruction by the ALU

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7
Q

How does the ALU use accumulators?

A

The ALU uses accumulators to store instructions in them that can be changed to other instructions.

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8
Q

Which are the special purpose registers and what do they do?

A

CIR (Current Instruction Register) - store current instruction while executed
PC (Program Counter) - stores the address of where the next instruction is to be read from.
IX (Index register) - Stores a value for indexed addressing
MAR (Memory Address Register) - Stores the address where the CPU is going to read from or write to a value
MDR (Memory Data Register) - stores data that was read from a memory or is about to be written into a memory because it is closer to the processor.
SR (Status Register) - operates as a flag so it will signal certain errors or situations

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9
Q

What is a system bus?

A

A system bus is a parallel transmission component with each separate wire carrying a single bit.

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10
Q

What is crucial to remember about a system bus?

A

A system bus isn’t a storage device.

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11
Q

What does a system bus consist of?

A

Address bus
Data bus
Control bus

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12
Q

What is an address bus do?

A

The address bus is a component that carries an address to the memory controller from the MAR to identify and address where data is to be read from or written to.

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13
Q

What can identify how many addresses an address bus can carry?

A

The number of wires is defining how many addresses an address bus can carry.

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14
Q

What kind of bus is an address bus?

A

An address bus is a one way bus.

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15
Q

What does a data bus do?

A

Carries data to and from the processor

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16
Q

What is the typical word length of a data bus?

A

16 bits, 32 bits of 64 bits.

17
Q

What kind of bus is a data bus?

A

A data bus is normally a bidirectional bus.

18
Q

What does the control bus do?

A

The control bus sends clock cycle signals to the component so that it receives the time when the data was sent.

19
Q

What kind of bus is a control bus?

A

A control bus is normally a bidirectional bus.

20
Q

How many wires does a control bus normally have?

A

The control bus typically has just 8 wires, no need for more.

21
Q

What is a Universal serial buses purpose and abbreviation

A

Universal serial bus is a data bus that allows to connect external devices and its abbreviation is USB.

22
Q

What happens in a fetch execute cycle?

A

The data or instruction is fetched than decoded and finally executed.

23
Q

What is register transfer notation?

A

Register transfer notation is a notation protocol to describe the process.

24
Q

What could some reasons for an interrupt to be generated?

A
Fatal error in the program
Hardware fault
A need of I/O process to begin
User interaction
Timer signal
25
Q

When is the interrupt handled?

A

The interrupt is handled only at the end of the fetch-execute cycle.

26
Q

What happens at the moment of the interrupt?

A

At the moment of interrupt the system stores the content of the
program counter and any other register involved.

27
Q

What is an ISR?

A

ISR is the Interrupt Service Routine program that is loaded after an interrupt has happened.

28
Q

What are the steps taken after the system stores the content of the program counter and any other register involved?

A

Step 1 The start address of the ISR is loaded to the PC
Step 2 The ISR checks if further interrupts are need to be handled
Step 3 If there are no more interrupts the ISR restores the original PC and the registers that were saved when the intrerrupt kicked in at the beginning.