Lesson 3.1: Computer architecture
When you have completed this chapter you will:
To explain the individual parts of a computer and their functions.
Know what does the processing part
To recognize the regional units and ranks them according to their function
To list the functions of the central processing unit
To explain the role of memory and the corridor to a computer
3.1.1. Introduction
In our daily lives then we come into contact with computers. The computer is a device that processes data by performing a series of commands that call the program.
Figure 3.1.1: Computer
In this chapter we will examine in detail how a computer is constructed and its operation.
3.1.2. Peripherals (peripheral units) and part processing
A very simple calculator is the calculator. The calculator has:
a keyboard with which we give the numbers and act that we perform
the part that processes the data we, that performs operations, and gives the result on screen.
and finally a small display in which the numbers and give the result of acts performed
Figure 3.1.2: The calculator
When you want to perform an arithmetic operation, eg "5" "+" "7", the calculator give the corresponding data using the keyboard. The processing section performs the taste and displays the result on screen.
Consider step - step what is happening inside the calculator, for example when you press the button "5":
Step 1 - The processing part is activated by pressing the record button and clicked. This process is called reading the keyboard and say that he read part of the processing key "5" from the keyboard.
Step 2 - To remember the part of the processing key was pressed, the internal caches to memory and say that the processing part outputting the key "5" in memory.
Figure 3.1.3: The calculator function
Step 3 - The processing part displays the "5" on the screen. This process is called a record and say that he wrote part of the processing or display the number "5" on the screen.
Similarly we introduce the "+" and the next number is "7". After reading the "7", the processing section performs the arithmetic operation 5 +7 = 12 and gives the result on screen. This operation is performed at the Central Processing Unit (CPU). The CPU adds the second number (7) with the number in its memory (of 5) and the result is displayed.
In summary we can generally distinguish two main parts to a computer hardware:
the processing part
and peripherals
The processing department is responsible for temporary storage, handling and processing of data into the computer. These peripherals are used to
1.Introduction data (keyboard, digital camera etc.)
2.apeikonisi data (monitor, printer, etc.) and
3.monimi data storage (hard disk, floppy, etc.)
3.1.3. The architecture of a computer
The processing department as we have said, is part of the computer which makes temporary storage, handling and processing. Specifically, this section comprises:
from memory (memory), which stores the program that we want to execute and data to be processed by the program
by the Central Processing Unit (CPU) (Central Processing Unit - CPU), running the commands of the program
and the runway (Bus) which allows the movement of data. It serves to communicate the CPU and memory, and communication with peripherals
The regional units are divided into three main categories according to their function. The regional units that supply data to a computer are called input and for example the keyboard and mouse.
The peripherals that take data from one computer and show in some form (letters, image, sound) are called output units. Such are the monitors, printers and speakers.
Finally, regional units in which there are stored programs or data storage units are on the computer. Such are the hard drives, floppy disks and optical disks CD.
Figure 3.1.4: The structure of a computer
Note the direction the arrows are in Figure 3.1.4:
In the case of input modules, the CPU reads (receives) data from the input modules.
In the case of units of output, the CPU writes (giving) the data output units.
And finally, the CPU can either write or read data from storage units
3.1.4. The Central Processing Unit
The heart of the computer is the Central Processing Unit (CPU). The CPU performs the commands of the program. All commands of the program is stored in computer memory.
The CPU begins reading the first instruction of the program. The process of reading a command from the memory recall phase is called the order.
After the read command followed by a phase of execution.
Consider the simplified calculator 3.1.5 shape and look very simple program that performs.
Figure 3.1.5: The CPU withdraw and run 1
This program adds each time we give the number from the keyboard and screen.
The CPU will start executing the command 1. This command waits to be pressed a key. If pressed goes to read the keyboard. Immediately after you run the second command. 2 The command will add the number read from the keyboard to the existing aggregate. Once you visualize the result of adding the screen, by running 3, the CPU will return to the top 4 with the command to wait for the touch of a button again.
As we conclude easily, all you can do this computer with this program is to continually add and if any key press, and shows the result of addition.
In Figure 3.1.5, the display shows the value 38, which is the sum so far. The CPU reads the first instruction from memory (recall phase). The CPU then executes the command and is waiting to press a key to read it. Suppose we press the 2 key. The CPU reads the number 2, the keyboard and ready to proceed to the next command.
Figure 3.1.6 The CPU executes the order of addition
As in the previous command to the CPU must first read the instruction from memory. The CPU recognizes that this command add the number you just entered, with the existing aggregate and perform the addition (execution phase) (Fig. 3.1.6).
Figure 3.1.7 The CPU executes the recording
After the execution of the instruction 2 followed by withdrawing the instruction phase 3, when the CPU gives the result on the screen (Fig 3.1.7).
Figure 3.1.8 The CPU executes the 4
Finally recalled from memory the command 4. The execution of this mandate, has led to go back to the first command and xanaperimenoume the touch of a button.
The CPU then performs commands, one after the other, even when "apparently" does nothing. So in our example, even when not press any button, the CPU performs constantly waiting for a command 1 new number.
Each CPU is designed to recognize only certain commands. The set of commands that can perform a repertoire called CPU commands. Most CPUs can perform arithmetic addition (ADD), withdrawal (SUB), multiplication (MUL) or division (DIV) integers. They also command execution logic operations (or (OR), and (AND), not (NOT)) and comparisons of results for operations (greater than zero, less than zero, etc.). Finally, the CPU commands are used to transfer data from memory and input modules and to the memory and output units.
3.1.5. The Memory
The memory is stored in the space program and data. In the example in the previous paragraph, were stored in memory only the commands of the program while keeping the data inside the KME. Most often, the CPU may not contain all data and program storage need them. The data is stored in memory in a separate area from the one stored program commands.
Memory we can imagine as a huge number of "boxes", which we call memory locations. Each position has a certain number that characterizes it, and they call at (address). At each position corresponds to a different address. If you want to write or read a memory location must know the address.
Often we say that "the contents of the address is 125 2 'rather than' content with the location address is 125 2."
Figure 3.1.9: Memory
The CPU can store data in a memory location, when talking about recording (write) memory.
Suppose, for example, the CPU executes the command "Write 3 at number 59." The CPU will give the memory address to which it wants to write and the data, ie the number "59". The memory then stores the number "59" in place to address 3. The old contents of a memory location, replaced with new data that give a time.
Figure 3.1.10: Register to memory
The CPU can also be informed of the contents of a memory location. We say then, that the CPU reads (read) the contents of this box and we read of memory. Reading a memory location does not change the content of the data that remains in this position.
The way that reads the contents of a memory location the CPU is similar to the way you wrote it. The CPU provides the address of the location he wants to read the memory and returns the contents of this box.
Figure 3.1.11: Reading the memory
In memory except the data is entamiefmenes commands and running programs. It should be understood that, as the data read from the memory locations with the same procedure, read and write commands. That is, each time the CPU must provide the memory address containing the next instruction to be executed. For this reason, the CPU keeps the internal address of the location containing the next instruction of the program. The process of reading commands from the memory corresponding to recall phase (fetch) of the order.
3.1.6. Hallway
As we have seen, the process of reading a given or an instruction from memory requires the exchange of information between memory and CPU for the process to succeed.
Similar information was exchanged and the CPU to communicate with peripherals.
All this information is exchanged in the form of electrical signals on the corridor. The corridor is the set of lines and circuits that take part in the movement of data between KME and memory or peripherals.
Please note that any given time only one can be moved to the hallway. For example, it can at the same time the CPU writes to memory and to import and one from a given input unit. Also from the devices connected to the corridor, only two can communicate any time with one to send data and another to receive.
The corridors do not serve only to transfer data between KME and memory or CPU and peripherals. Even the peripherals can communicate directly to memory using the corridor. This technique is called direct memory access (Direct Memory Access - DMA). With this technique, the CPU does not need to be inserted in the transfer of data from input modules, output and storage units to the system memory, resulting in the transfer of these to be faster.
Figure 3.1.12: DMA Transfer
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3.1.7. Peripherals
The CPU, memory and corridors are part of the computer that runs the program and processes the data, ie the processing department. All other devices used in a computer are the regional units. The regional units, as we have already said, perform three main functions in a computer:
Input (keyboards, switches, cameras, sensors)
Output data (computer screens, liquid crystal displays - LCD, led) and
Data storage (hard disks, optical disks). The media are needed for storing large amounts of data.
The peripheral devices are an integral part of a computer. Without them the computer would be impossible to accept data from its environment and presents the results in the required format. The large number of peripherals, contributed significantly to the widespread use of computers in all fields of science and everyday life.
What I learned:
The two main parts of the computer is the processing part and peripherals.
The processing part consists of memory, CPU and hallway.
The processing department is responsible for handling and processing of data by following the instructions of the program.
The regional units are divided into input units, output units and storage units.
The Central Processing Unit (CPU) continually withdraw instructions from memory and executes them.
In memory stores the program instructions and data.
The corridor connects the CPU to memory and peripherals.
You learned how data is transferred:
from CPU to memory and vice versa
from the CPU to peripherals and vice versa
In direct memory access (DMA) data moved between memory and peripherals without the intervention of the CPU.
Terminology
Processing Department
Peripherals (Peripheral Units)
Units of Input, Output Units, Storage Units
CPU (Central Processing Unit)
Revocation of Order (Instruction Fetch)
Execution (Instruction Execution)
Memory (Memory)
Address of Memory (Memory Address)
Reading from memory
Register to memory
Corridor (Bus)
Direct Memory Access (Direct Memory Access)
Control knowledge
1.The computer runs that _________ withdraws from _______. The entire program is _________.
2.Diakrinoume two parts in a computer: The section _______ and __________ units.
3.The processing part consists of _________________________, the _________ and _________.
4.The CPU reads data from the units ________.
5.The _______ CPU output data in units and uses the storage unit for storing _________.
6.Otan the CPU reads instructions from memory talking about _______ phase of the order.
7.The next step is ______ phase of the order.
8.The memory is the ________ space for data and program instructions.
9.Kathe memory location designated by the _________.
10.O corridor connects the CPU with the _________ and __________ units.
Match the words on the right with the words on the left column:
CPU
Input unit
Temporary Storage
Output unit
Hard disk
Processing Department
Keyboard
Memory
Sound Card
Storage Unit
