Computer System Architecture NDCSA2 Low level components

This is the brain of the computer. It processes everything from basic instructions to complex functions. Anything that wants to get calculated it gets sent to the CPU.

It transfers data between components inside a computer or between computers.  The width of a data bus refers to the number of bits (electrical wires) that make up the bus. Common data bus widths include 1-, 4-, 8-, 16-, 32-, and 64-bit.

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DATA BUS

Is the part of the computer that performs all the arithmetic calculations such as addition and multiplication and all comparison operations. The ALU is a component of the CPU.

 

                                                                                                                                                

                                                                                                                                                

CPU ALU

I/O

Once data has been written onto a ROM chip, it cannot be removed and can only be read.

RAM/ROM

 

                                                                                                                                                

                                                                                                                                                

 

ADDRESS BUS

                                                                                                                                                 MEMORY

Volatile memory is used by the system to store data for processing by a computer's (CPU). RAM stores the data in memory cells that are arranged in grids from which data, in the binary form of 1's and 0's, can be accessed and transferred at random to the processor for processing by the system's software. When you shut down the computer nothing stays on the RAM.

Is used to describe any program operation or device that transfers data to or from a computer and to or from a peripheral device. For example if you’re running word program and type a sentence on your keyboard the text will appear on the screen. The keyboard is an input device and the screen is an output device you can also print the text which is also an output device.

Is a collection of wires connecting the CPU with the main memory this is used to identify particular locations in the main memory. Is also used to transfer data between devices and physical address to communicate read/write commands. All address busses are read and written by the CPU or DMA in the form of bits.

 

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RAM-

RAM stands for Random Access Memory. Volatile memory is used by the system to store data for processing by a computer's (CPU). When you shut down the computer nothing stays on the RAM. Prices range from £10 to £100 depending on the quality. There are many types of DDR RAM but the most recent one is DDR3. RAM starts from 800 MHz to 1333 GHz as standard. RAM can be overclocked to improve performance. Ram performs really fast.It’s a permanent storage data is lost when motherboard doesn’t have power.

CACHE-

CPU cache has three points that it’s placed. Point one the cache is built in the CPU, point two the cache is separated from the CPU but located near it on the motherboard and point three is where both point one and two are built in the CPU and placed near the CPU on the motherboard. Cache that is built into the CPU is faster than separate cache. Cache is more expensive than RAM, but it is worth getting a CPU and motherboard with built-in cache in order to maximize system performance. A cache is a form of storage is used to recover data at any time, mostly is used in browsers to load webpages quicker that have been previously opened because the basic data has already been stored and so is quicker than downloading the data again from the beginning. Programs store the cache so next time its available. However, the cached data is volatile and once the system is turned off it is erased.

FLASH-

It’s a type of storage. EEPROM stand for Electrically Erasable Programmable Read-Only Memory and erases 1 byte at a time. Flash is faster to deleting data also flash has no moving part and its likely to break. Flash is becoming ever more popular and its storage capacities rising every year. Flash is popular in portable electronics, especially in phones, cameras (SD cards) and other portable devices. Flash is non-volatile storage, which means once the PC has been powered down completely, it remembers the data when you turn it back on. You also get a less amount of storage because it’s more expensive. The cost of flash is expensive compared to a normal 3.5” hard drive.

REGISTERSS-

In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. General purpose registers are available to store any transient data required by the program. In general the more registers a CPU has available, the faster it can work.

The CPU also contains a number of special-purpose registers:

Instruction Register (IR): The instruction register stores the instruction while it is decoded and prepared ready to be executed.

Memory Data Register (MDR): The memory data register keeps the piece of data that has been taken from the memory.

Memory Address Register (MAR): The memory address register holds the address of the next piece of memory to be picked up.

Program Counter (PC): The program counter holds the address (location) of the next instruction to be fetched from memory.

Accumulator: The accumulator is an internal CPU register used as the default location to store calculations performed by the arithmetic and logic unit.

http://www.sqa.org.uk/e-learning/CompArch03CD/page_02.htm

SECONDARY STORAGE-

Secondary storage, sometimes called auxiliary storage. Is all data storage that is not currently in a computer's primary storage. On a personal computer secondary storage could be external hard drive, CD or DVD or on any removable media. Is a storage medium that holds information until it is deleted or overwritten.  You can access primary storage much faster than a secondary storage because of the price and size limitations secondary storage is used with today's computers to store all your programs and your personal data. Also media can be removed from the computer and stored elsewhere.

Reference:This picture is from my own work that I used in a different assignment.

 

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Computers work with data. They read, write, transform, calculate and modify it. When data is being used, it is stored in the computer's Random Access Memory, or RAM. When a computer is working with a large amount of data, memory space can run out. Running out of memory can cause the computer to slow down, or even to become unstable.

http://www.technick.net

A computer uses RAM to hold temporary instructions and data needed to complete tasks. This enables the computer’s CPU (Central Processing Unit), to access instructions and data stored in memory very quickly.

The RAM is the temporary memory used to load the OS and other programs and applications while he PC functions. It is a dynamic memory which can read and write data ( does both) as far as the power is ON. And the processor accesses it to receive any particular data required to be processed and it stores temporarily the data that we input when a particular program runs.
The BIOS which boots the PC and searches and loads the OS to the RAM does it from ROM which is a computer chip on which the data is stored permanently on it and can't be modified i.e nothing can be written into

1)    Fetch: The Fetch Operation is used for taking the instructions those are given by the user and the Instructions those are stored into the Main Memory will be fetch by using Registers.

2)    Decode: The Decode Operation is used for interpreting the Instructions means the Instructions are decoded means the CPU will find out which Operation is to be performed on the Instructions.

3)    Execute: The Execute Operation is performed by the CPU. And Results those are produced by the CPU are then Stored into the Memory and after that they are displayed on the user Screen.