Computer Organisation

Question 1

What is the i/o system?

Answer 1

Allows the computer to communicate with the outside world and store data while the power is off

Question 2

Give an example of non-storage devices?

Answer 2

Keyboard, mouse, monitor, and speakers

Question 3

Give another name for a storage device?

Answer 3

Auxilary device and they are categorized as either magnetic or optical

Question 4

How optical and magnetic storage work

Answer 4

pg 98-104

Question 5

How are the CPU and memory connected?

Answer 5

BY three groups of connections; each carrying one bit at a time. The number of connections depends on the size of the data being transferred.

Question 6

What is the address bus?

Answer 6

It allows access to the memory.

The number of connections depends on the address space of the memory.

Question 7

What is the data bus?

Answer 7

Its made of several connections; each carrying one bit at a time. The number of connections depends on the size.

Question 8

What is the control bus?

Answer 8

Carries communication between the CPU and memory so there is a code sent from the CPU to memory to request a read/write operation.
The number of connections is determined by the number of control commands.
The computer needs 2^m control actions, we need m connections

Question 9

How are I/O devices connected to the CPU and memory?

Answer 9

Through controllers which can be parallel or serial.

Question 10

Give examples of controllers?

Answer 10

SCSI, FireWire, USB, and HDMI. More information on pg 106-108

Question 11

What does a machine cycle consist of?

Answer 11

Fetch, decode, and execute

Question 12

Explain the fetch phase

Answer 12

1. The control unit orders the system to be copied into the instruction register.
2. The address of the instructions to be copied is held in the program counter register.
3. Once copying is done, the program counter is incremented to execute the next instruction.

Question 13

Explain the decode phase?

Answer 13

Once the instruction is in the instruction register it is decoded by the control unit into binary code so the system can perform an operation with it.

Question 14

Explain the execute phase?

Answer 14

The control unit will tell the system to read or use ALU to form operations with it.

Question 15

What is programmed I/O?

Answer 15

The transfer of data between CPU and I/O device as the CPU constantly checks I/O waiting for data to transfer it. It does nothing else until the transfer is complete.

Question 16

What is the interrupt-driven I/O?

Answer 16

The I/O device will interrupt the CPU when ready to transfer data allowing the CPUs time not to be waisted. Some as programmed I/O data goes to memory after input, data is from memory before output.

Question 17

What is DMA?

Answer 17

Direct memory access is used to transfer large blocks of data between high-speed I/O devices (like a disk) without using the CPU. The DMA controller manages the data as it has registers to hold on to a block of data; the CPU will send a message containing the type of transfer (input/output), the beginning address of the memory location, and the number of bytes to be transferred. DMA allows the CPU to do other tasks and it will tell the CPU when it needs access to the buses. The CPU will start idling allowing the controller to make its transfers.

Question 18

What is CISC? (complex instruction set computer)

Answer 18

The strategy behind the architecture is for programming to be easier as there is a single instruction for complex and simple tasks. The architecture has a large set of complex and single instructions this makes the CPU and control unit very complicated. eg Pentium

Question 19

How do you reduce the complexity of the CPU and control unit in CISC?

Answer 19

The CPU only does simple operations and if there is a complex operation it is broken down into simple operations(micro-operations). Allowing micro-operations requires memory (micro-memory) to hold the set of complex operations.

Question 20

What is RISC?

Answer 20

‘Reduced instruction set computer’ is to have a small set of instructions that do a minimum amount of operations. Complex instructions are broken down into subsets. Programming in RISC is more complex and time-consuming than the other ways.

Question 21

What does the CPU consist of?

Answer 21

ALU, control unit, and a set of registers.