cambridge computer science as unit 5

The 5 basic features of the Von Neumann model.

• There is a processor (CPU)

• The processor has direct memory access

• Memory contains 'stored program' and data required

• The stored program consists of individual instructions

• The processor executes instructions sequentially

Fill in 1.

Address Bus

Fill in 2.

Data Bus

Fill in 3.

MAR

Fill in 4.

MDR

Fill in 5.

PC

Fill in 6.

Control Bus

Fill in 7.

Control Unit

Fill in 8.

CIR

Fill in 9.

ALU

Fill in 10.

Other Registers

What does CPU stand for?

Central Processing Unit

What does ALU stand for and what is its function?

Arithmetic Logic Unit. It does arithmetic and/or logic operations.

What does CU stand for and what are its functions?

Control Unit. It controls data flow through processor and rest of computer, ensures program instructions are handled correctly. A vital part of the CU is the two clocks used to synchronize processors.

Which components have an active role in the CPU operations?

Arithmetic Logic Unit (ALU) and Control Unit (CU)

How many clocks in the CU? What are they called?

There are two clocks: the internal clock and the system clock.

What is the function of the internal clock?

Controls cycle of activity within the processor.

What is the function of the system clock?

Controls activity outside the processor.

What are registers and where are they placed?

They are storage units placed very close to the ALU.

What are the benefits of registers for where they are placed?

Allows very short access time.

What are the typical storage size of registers?

Typically 16, 32, or 64 bits

A processor has just one general purpose register. What is it called?

Accumulator

What is the function of the accumulator?

It is a general purpose register that stores a value before & after the execution of an instruction.

How many values are stored in an accumulator at one time?

A single value.

What uses the valued stored in the accumulator?

The ALU

What is CIR?

Current Instruction Register. Stores the current instruction while it is being decoded and executed.

What is IX?

Index register. Stores a value; only used for indexed addressing.

What is MAR?

Memory Address Register. Stores address of a memory location or an I/O component which is about that have a value read from or written to.

What is MDR (MBR)?

Memory Data Register (Memory Buffer Register). Stores data that has just been read from memory or is just about to be written to memory.

What is PC?

Program counter. Stores the address of where the next instruction is to be read from.

What is SR?

Status Register. Contains bits that are either set or cleared which can be referenced individually.

What are the three important things to remember about registers?

• The MDR must act as a buffer.

• The index register (IX) can be abbreviated as IR, but in some sources the current instruction register (CIR) is abbreviated as IR.

• To avoid confusion, PC stands for Program Counter only when register notation is used; otherwise, it stands for Personal Computer.

A bus is a __.

parallel transmission component.

In a bus, each separate wire carries a __.

single bit

The system bus connects the CPU to what?

Memory & I/O system

What components make up the system bus?

Address bus, data bus, and control bus

Is arrow 1 up, down, or both?

Both

Is arrow 2 up, down, or both?

Down

Is arrow 3 up, down, or both?

Both

Is arrow 4 up, down, or both?

Both

Is arrow 5 up, down, or both?

Up

Is arrow 6 up, down, or both?

Both

Is arrow 7 up, down, or both?

Both

Is arrow 8 up, down, or both?

Up

Is arrow 9 up, down, or both?

Both

Address bus is a __ way street.

one

Address bus can only be used to __ an address.

send

__ __ are a component that carry data to the memory or to an output device or can carry data from memory or from an input device.

Data bus

What is the function of the data bus?

To carry data

The data bus is __ way

two (bi-directional)

The data bus can carry data to and from the ___.

CPU or I/O device.

What is bus width?

The number of parallel lines that make up a particular kind of computer bus. It is one of the most vital defining features of a data bus. It indicates the number of electric wires or bits that build up the data bus.

What are some common bus widths?

1, 4, 8, 16, 32, and 64 bits

Is the control bus one way or bidirectional?

Bidirectional.

What is the function of the control bus?

Transmits a signal from the control unit to any other system component or transmit a signal to the control unit. Major use is to carry timing signals at time intervals dictated by the clock cycle ensuring data transmission is synchronized.

How many wires for the control bus?

Eight wires because there is no need for extended width.

Which bus is connected to the Control Unit?

Control bus

Which bus is connected to the MAR?

Address bus

Which bus is connected to the MDR?

Data bus

What is very important factor governing the processing speed of the system?

Processor clock speed

What defines the shortest possible time that any action can take?

One clock cycle

Immediate Access Storage (IAS)

The components directly accessible by the processor.

Each core is a __ processor.

separate

Performance improves with __ number of cores.

increasing

Cache memory is the __ component of the IAS.

fastest

Performance of cache memory improves with __ storage size.

increase

Performance of cache memory improves with __ rate of access.

increase

How is fastest access obtained for cache memory?

With all or part of the cache on the CPU.

What is a word?

Small number of bytes that handled as unit by the computer system.

What is the significance of word length?

Defines a grouping the system can handle as one unit.

How is word length stated?

Number of bytes or number of bits.

What are some typical word lengths?

16, 32, or 64 bits or 2, 4, or 8 bytes.

Word length influences system architecture in regards to __ of components.

capacity

How are register size and word length usually related?

Both match

Word length is considered when making bus __ decisions.

width

For address bus, what does bus width define?

number of bits in the address's binary code

How are data bus width and word length related?

Data bus width is the same as word length

Each I/O device is connected to an interface called __

port

This handles the interaction between the CPU and an I/O device.

The controller

This type of port is connected to an I/O device that is an integral part of the computer system?

Internal port

This type of port allows the computer user to connect a peripheral I/O device.

External port

What does USB stand for?

Universal Serial Bus

What is the aim of plug and play?

Remove technical expertise allowing any computer user to connect a peripheral.

The creation of what device allowed Plug-and-Play to be fully realized?

USB

What is the alternate to USB?

FireWire

According to the USB standard, how many attached devices can a computer handle?

127

According to the notes, what is the latest USB version?

3.2

According to Google, what is the latest USB version?

4

What does VGA stand for?

Video Graphics Array

What is VGA sometimes needed?

One example: To connect a second screen.

Does VGA provide video, audio, or both?

Video only

What does HDMI stand for?

High Definition Multimedia Interface

How is HDMI different from VGA?

HDMI provides a connection to a screen and allow transmission of high-quality video including the audio component. VGA only provides video.

Fill in 1.

Start

Fill in 2.

Any instructions to execute?

Fill in 3.

Fetch next instruction

Fill in 4.

Decode instruction

Fill in 5.

Execute instruction

Fill in 6.

Any interrupts to be processed?

Fill in 7.

Transfer control to interrupt-handling program