Flashcards in Computer architecture Deck (49):
Computer systems consist of software and hardware. What is meant by each term?
- Software: programs executed from a computer system/ instructions that tell the hardware what to do.
- Hardware: electrical component that makeup a computer system
What is meant by the microprocessor or CPU?
A semiconductor chip that implements the central processor of the of a computer.The microprocessor is the component that executes instruction in a sequence.
Name and describe the functions of the main components within the Von Neuman CPU.
1. Control Unit: provides the functionality required to control the movement of information between memory, the ALU an other portions of the machine.
/ is in charge of fetching the sequence it also decodes, synchronises and sends control signals between different internal parts.
2. ALU (Arithmetic Logic Unit): Forms functions of two input values and produces a single output result/ performs arithmetic and logical operations.
3. Registers: very small but fast storage located on the CPU
4. Buses: connect all internal components (CPU with main memory).
Define Main Memory
Volatile memory that stores instructions and data which is directly accessible by the processor.
Purpose of Main Memory
For storing programs that are currently being run and for data that is currently being processed.
Example of what is stored in Main Memory
A spreadsheet with its data that a user is currently working on.
Is small but fast memory which can be used by the processor much more quickly.
Purpose of Cache
To be accessed quicker than RAM by the CPU.
Example of what is stored in Cache
Instructions used for a loop that the processor is currently executing.
Small but fast temporary storage located on the CPU.
Purpose of Register
Stores one instruction to be executed next.
Example of what is stored in a Register
LDA#15 - Load number 15 into accumulator.
Define ROM (Read Only Memory)
Series of instructions inside a computer that cannot be changed - non volatile.
Purpose of ROM
For data and instructions that are fixed onto the ROM chip to start the computer.
Example of what is stored in ROM
Configuration of the motherboard.
Define EEPROM (Electronically Erasable Programmable Read Only Memory)
Is non volatile but the entire contents can be erased and reprogrammed.
Purpose of EEPROM
Holds details of what is connected to the motherboard.
Example of what is stored in EEPROM
Multiple numbers and configurations of RAM modules
Example of secondary storage
Example of Main Memory
What is meant by CACHE memory
CACHE is small but fast memory that can be used by the processor much quicker compared to RAM. While CACHE is quicker, RAM has a higher capacity. Also RAM is volatile memory that stores instructions and data which is directly addressable by the processor.
CACHE: parts of the program currently being used.
RAM: All running programs.
Describe three differences between RAM and ROM?
- RAM is volatile
- ROM is non volatile
- RAM larger capacity
- ROM smaller capacity compared to RAM
- ROM does not require a constant source of power to retain information stored on it
- RAM does require a constant source of power to retain information. When power is turned off RAM will lose all information stored on it
What is the difference between ROM and EEPROM?
ROM: Cannot be changed
EEPROM: Content can be erased and reprogrammed
ROM: Systems / Programs / Instructions to boot your computer
EEPROM: Configuration of the motherboard attached devices
Computers utilise different types of cache memory. Two traditional types of RAM cache and disc cache. Describe in detail each type of cache memory.
1. On-chip cache: Area of microprocessor that contains cache memory.
2. Disc cache: Area of very fast memory between a hard drive and RAM.
3. RAM cache: Area of very fast memory between RAM and the microprocessor.
4. Web Cache: File containing recently accessed web pages.
Another use of cache is storing internet pages temporarily on the computer's hard disc drive. Briefly describe the advantages of utilising this type of cache.
This cache (web cache) speeds up viewing because you can quickly view previously viewed pages.
What is the highest address in a computer with 1K of memory?
2^10 - 1
Give three examples of what can be stored in a 32 bit word.
Values / characters / integers
A particular computer has 256 MB of RAM. How many bus wires are needed to address every Byte of this memory?
1MB = 2^20 --(20 lines)
256MB = 2^20 * 2^8 = 2^28 -- (28 lines)
Giving an example in each case, define the computer terms bit and byte.
Bit: One binary digit, smallest unit of data in a digital computer system, can store one value (Example: 0 or 1).
Byte: A group of 8 bits (Example: 0101 0101).
Define the computer term word. Give an advantage of a computer using a large word size compared with a computer using a small word size .
Word - the number of bits processed in one go in CPU.
Advantage - quicker than smaller word size because it can transfer more bits in one go.
A word is the number of bits which can be addressable or transferred as a single unit at a time. A computer with a large word size will be faster compared to a computer with a smaller word size.
Advantage: performance better because more instructions.
What is meant by the stored program concept?
Program must be resident in Main Memory to be executed. From where they are fetched one after another, one at a time. Program can be replaced by loading another program into main memory.
What is meant by a Von Neuman architecture?
Programs/ instructions and data are stored in one single store (MAIN MEMORY).
Give two more names for immediate access store
RAM and Main memory
Give another name for main memory
If the data bus consists of 8 lines, what is the largest denary value which could be transferred in one go?
What is the significance of the size of the address bus?
It determines the number of memory cells that can be accessed by the CPU
Give two examples of a signal carried by the control bus
- Command signals
- Timing signals
What are the names of the three buses
- Data bus
- Control bus
- Address bus
A company has designed a new peripheral and is developing the I/O controller for it.
What do we mean by the term peripheral?
A peripheral is a piece of equipment that can be attached to the central processing unit, e.g. hard disk, keyboard (I/O controller).
Why are devices not connected directly to the processor?
It would slow the computer down because the devices would have to have a separate interpreter in order to communicate
Name one other device controller which may be found in a typical microcomputer
The data bus carries data in both directions. Explain why the address bus only carries addresses in one direction
Does so from processor to system components. It only goes in one direction so no outside devise can write into the microprocessor.
What is meant by the clock speed of a processor
The number of pulses per second generated by an oscillator that sets the tempo for the processor
How is clock speed measure?
What is the relationship between the word length and bus width of a processor?
Bus width - determines the number of bits that can be transmitted together.
Word length - number of bits that the processor can process simultaneously
Identify and describe three factors that affect the rate at which operations are carried out by the microprocessor.
1. Control Unit - coordinates the activities taking place in the processor memory and peripherals.
2. ALU - in which all arithmetic and logical operations are carried out.
3. System Clock - generates clock pulses to step the control unit through its operations.
What is the effect on processor performance of increasing (1) clock speed, (2) word length and (3) data bus width?
1. If clock speed increases the speed at which instructions are executed increases in the processor.
2. The overall speed of the computer will increase with the increase of word length.
3. Determines the overall speed and performance.
Why are microprocessors being designed with multiple cores?
- They become faster
- Clock frequency increases with multiple cores