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Computer Science > SLR1- Structure and Function of the Processor > Flashcards

SLR1- Structure and Function of the Processor Flashcards

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1
Q

What is the purpose of the Control Unit?

A
  • Coordinates all activities of the CPU
  • Directs flow of data between CPU and other devices
  • Accepts the next instruction, decodes it, handles execution and stores data back in memory or registers.
  • Sends read and write requests to main memory on the control bus, as well as other requests such as interrupt requests.
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2
Q

What is the purpose of the Program Counter?

A
  • Holds the address of the next instruction to be executed (could be next in sequence or address to jump to if current instruction is a jump or branch- copied from CIR)
  • At the end of FDE cycle the address held in the PC is copied to the MAR
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3
Q

What is the purpose of the MAR?

A
  • Holds the address or memory location from which data or an instruction is to be fetched or to which data is to be written.
  • Sends the address to memory down the address bus.
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4
Q

What is the MDR used for?

A
  • Used to temporarily store the data which is read from or written to memory.
  • Sometimes known as the MBR (memory buffer register) also nicknamed the gateway to the processor.
  • All data from memory must travel down the data bus and pass through the MDR
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5
Q

What is the purpose of the Current Instruction Register?

A
  • Holds the current instruction being executed.
  • Contents of MDR are copied to CIR if it is an instruction.
  • Contains the opcode and operand(s) of the current instruction
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6
Q

What is the purpose of the Arithmetic Logic Unit?

A
  • Performs arithmetic and logical operations on data.
  • Arithmetic operations on fixed and floating point numbers
    • ADD
    • SUBTRACT
    • MULTIPLY
    • DIVIDE
  • Bitwise shift operations left and right.
  • Boolean logic operations
    • AND
    • OR
    • NOT
    • XOR
    • Comparison
  • Often uses general-purpose registers to store results of calculations such ass the accumulator
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7
Q

What is the purpose of the Accumulator?

A
  • One of many general-purpose registers.
  • Data control info is often stored in them.
  • Typically, the more general-purpose registers a processer has, the faster it may operate.
  • Results of ALU calculations are often stored here.
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8
Q

What is the purpose of the Address Bus?

A
  • Carries memory addresses that identify where the data is being read from or written to.
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9
Q

What is the purpose of the Data Bus?

A
  • Carries the binary 1’s and 0’s that make up the actual information being transmitted around the computer
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10
Q

What is the purpose of the Control Bus?

A
  • Carries command and control signals to and from every other component of the CPU/Computer
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11
Q

What is add in assembly code?

A

ADD

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12
Q

What is subtract in assembly code?

A

SUB

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13
Q

What is store in assembly code?

A

STA

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14
Q

What is load in assembly code?

A

LDA

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15
Q

What is branch always in assembly code?

A

BRA

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16
Q

What is branch if zero in assembly code?

A

BRZ

17
Q

What is branch if positive in assembly code?

A

BRP

18
Q

What is input in assembly code?

A

INP

19
Q

What is output in assembly code?

A

OUT

20
Q

What is end program in assembly code?

A

HLT

21
Q

What is data location in assembly code?

A

DAT

22
Q

What happens during the fetch stage?

A
  • Program counter is checked.
  • Addressed store is then copied into the MAR
  • Address is then sent along the address bus to main memory where it waits to receive a signal from the control bus.
  • Control unit sends read signal along control bus.
  • Contents in address send along the data bus to the MDR and copied to the CIR
  • Program counter contents are incremented so that it points to the next address to be executed.
23
Q

What happens during the decode stage?

A
  • Instruction held in CIR is decoded by decode unit.
24
Q

Parts of an instruction?

A

Opcode: what to do
Operand: what to do it to

25
Q

What happens during the execute stage?

A
  • Address is sent to the memory address register.
  • Address sent down the address bus to main memory.
  • Control unit sends command signal along control bus to main memory.
  • Contents can then be sent along the data bus to the MDR
  • Contents of MDR copied to CIR
26
Q

How does a program branch?

A
  • Value in the program counter is replaced with the content of the operand from the current instruction register.
  • As program counter contents have been updated to a new memory location, the program can jump around memory.
27
Q

How does a program branch?

A
  • Value in the program counter is replaced with the content of the operand from the current instruction register.
  • As program counter contents have been updated to a new memory location, the program can jump around memory.
28
Q

What is clock speed measured in?

A

Hz

29
Q

What does clock speed mean?

A
  • Number of cycles per second.
30
Q

What is the cache used for?

A
  • Temporary storage of data and instructions being read to and written from.
  • Located on or near the CPU
  • Stores copies of recent data and instructions.
  • Much quicker to access than main memory (RAM)
31
Q

What factors affect the performance of the CPU?

A
  • Clock Speed
  • Cache Size
  • Number of Cores (note: doubling the number of cores doesn’t double the overall speed.)
32
Q

Key features of Harvard architecture?

A
  • Instructions and data stored in separate memory units.
  • Each has its own bus.
  • Reading and writing data can be done at the same time as fetching an instruction.
  • Used by RISC processors.
33
Q

Key features of Von Neumann architecture?

A
  • Shared memory space for instructions and data.
  • Instructions and data are stored in the same format.
  • A single control unit or processor follows a linear fetch-decode-execute.
  • One instruction at a time.
  • Registers are used as fast access to instructions and data.
34
Q

What are modern machine architectures known as?

A
  • Contemporary
35
Q

What is SIMD?

A
  • Single Instruction Multiple Data
  • Uses parallel processing.
36
Q

What does parallel processing do?

A
  • Carries out a single instruction on multiple pieces of data at the same time.
  • Often used by graphical processors.
37
Q

What is MIMD?

A
  • Multiple Instructions Multiple Data
  • Another type of processing that carries out multiple instructions on multiple pieces of data simultaneously.
38
Q

What is Distributed Computing?

A
  • Where multiple computers on a shared network each take on part of a bigger problem.

Computer Science (4 decks)

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