The computer architecture includes both a structure that reflects the composition of the PC and software and mathematical support. The structure of a computer is a set of elements and connections between them.
The basic principle of building all modern computers is program control. The foundations of the doctrine of computer architecture were laid by John von Neumann. The combination of these principles gave rise to the classical (von Neumann) computer architecture.
Von Neumann not only put forward the fundamental principles of the logical structure of a computer, but also proposed its structure, presented in the figure (draw in a notebook).
Rice. John von Neumann circuit
Von Neumann's provisions:
A computer consists of several main devices (arithmetic-logical unit, control unit, memory, external memory, input and output devices)
Arithmetic-logical unit - performs logical and arithmetic operations necessary to process information stored in memory
Control device – provides control and monitoring of all computer devices (control signals are indicated by dotted arrows)
Data stored in a storage device is in binary form
The program that runs the computer and the data is stored in the same storage device
Input and output devices are used to input and output information
One of the most important principles, the stored program principle, requires that the program be stored in the machine's memory in the same way that the original information is stored in it.
The arithmetic-logical unit and control unit in modern computers form the computer processor. A processor that consists of one or more large integrated circuits is called a microprocessor or microprocessor stack.
A processor is a functional part of a computer that performs basic operations for processing data and controlling the operation of other units. The processor is a converter of information coming from memory and external devices.
Storage devices provide storage of initial and intermediate data, calculation results, and programs. They include: random access memory (RAM), extra random access memory (SRAM), read only memory (ROM) and external memory (VRAM).
Operational memories store information with which the computer is working directly at a given time (resident part of the operating system, application program, processed data). RAM stores the most frequently used data by the processor. Only the information stored in SRAM and RAM is directly accessible to the processor.
External storage devices (magnetic disk drives, such as a hard drive or hard drive) with a capacity much larger than RAM, but with significantly slower access, are used for long-term storage of large amounts of information. For example, the operating system (OS) is stored on the hard drive, but when the computer starts, the resident part of the OS is loaded into RAM and remains there until the PC session ends.
ROM (read-only memory) and EPROM (reprogrammable read-only memory) are designed to permanently store information that is written there when it is manufactured, for example, EPROM for BIOS.
For example, a keyboard serves as an information input device. As an output device - display, printer, etc.
In a computer built according to the von Neumann scheme, instructions are sequentially read from memory and executed. The number (address) of the next memory cell from which the next program command will be extracted is indicated by a special device - a command counter in the control device.Law and CCA
Lesson 9. Backbone-modular principle of computer construction.
Assignment: using the educational text, answer the following questions (write in your notebook).
1. Who was the founder of the backbone-modular principle of modern PC architecture.
2. Computer architecture is...
3. List the basic principles underlying the backbone-modular construction of PC architecture.
4. What parts does the highway consist of?
5. What is the device interface for?
6. What is used to negotiate interfaces? How does this coordination work (draw a diagram)?
7. How is data processed on a computer?
8. Draw a schematic diagram of the backbone-modular principle of a PC.
9. The highway is...
10. What is the purpose of the control bus, address bus, data bus?
12. What does the modular principle allow the PC user? List the main advantages of the modular-backbone principle.
D/z. Answer questions, prepare to answer the educational text.
Educational text
Backbone-modular principle of computer construction
Let's remember the information received in previous lessons:
A computer is an electronic device designed to work with information, namely introduction, processing, storage, output and transmission of information. In addition, a PC is a single entity of two entities - hardware and software.
Computer architecture is a description of its logical organization, resources and operating principles of its structural elements. Includes the main computer devices and the structure of connections between them.
Usually, when describing the architecture of a computer, special attention is paid to those principles of its organization that are characteristic of most machines belonging to the family being described, and also that influence programming capabilities.
The architecture of modern computers is based on principles of John von Neumann and the backbone-modular principle.
In 1946, D. von Neumann, G. Goldstein and A. Berks, in their joint article, outlined new principles for the construction and operation of computers. Subsequently, the first two generations of computers were produced on the basis of these principles. There have been some changes in later generations, although Neumann's principles are still relevant today.
In fact, Neumann managed to summarize the scientific developments and discoveries of many other scientists and formulate something fundamentally new on their basis.
Von Neumann's principles
1. Use of the binary number system in computers. The advantage over the decimal number system is that devices can be made quite simple, and arithmetic and logical operations in the binary number system are also performed quite simply.
2. Computer software control. The operation of the computer is controlled by a program consisting of a set of commands. Commands are executed sequentially one after another. The creation of a machine with a stored program was the beginning of what we call programming today.
3. Computer memory is used not only to store data, but also programs.. In this case, both program commands and data are encoded in the binary number system, i.e. their recording method is the same. Therefore, in certain situations, you can perform the same actions on commands as on data.
4. Computer memory cells have addresses that are numbered sequentially. At any time, you can access any memory cell by its address. This principle opened up the possibility of using variables in programming.
5. Possibility of conditional jump during program execution. Despite the fact that commands are executed sequentially, programs can implement the ability to jump to any section of code.
6. Availability of information input and output devices. These devices are basic and sufficient for computer operation at the user level.
7. Open Architecture Principle– rules for building a computer, according to which each new block must be compatible with the old one and be easily installed in the same place in the computer. In a computer, you can just as easily replace old blocks with new ones, wherever they are located, as a result of which the operation of the computer is not only not disrupted, but also becomes more productive. This principle allows you not to throw away, but to modernize a previously purchased computer, easily replacing outdated units in it with more advanced and convenient ones, as well as purchasing and installing new units. Moreover, in all of them, the connectors for connecting them are standard and do not require any changes in the design of the computer itself.
The most important consequence of these principles is that now the program was no longer a permanent part of the machine (like, for example, a calculator). It became possible to easily change the program. But the equipment, of course, remains unchanged and very simple.
A computer is not an indivisible, integral object. It consists of a number of devices - modules.(The user can complete his computer from these modules at his own request). For each device in the computer there is an electronic circuit that controls it. This circuit is called a controller, or adapter. Some controllers can control several devices at once. All controllers and adapters interact with the processor and RAM through the system bus (a set of electronic lines. A bus is a cable consisting of many wires.
The backbone provides data exchange between computer devices.
The highway consists of three parts:
1. address bus, on which the address of the required memory cell or device with which information will be exchanged is set.
2. Data bus, through which the necessary information will be transmitted.
3. Control bus regulating this process. (signals are transmitted via the control bus that determine the nature of the exchange of information along the highway. These signals indicate what operation should be performed).
In order for a computer to function correctly, it is necessary that all its devices work together, “understand” each other and “do not conflict.” This is ensured thanks to the same interface that all computer devices have.
An interface is a means of connecting two devices, in which all physical and logical parameters are consistent with each other.
Since data exchange between devices occurs through the bus, to coordinate interfaces, all external devices are connected to the bus not directly, but through their controllers (adapters) and ports.
Ports can be serial or parallel. Slow or remote devices (mouse, modem) are connected to serial ports, and faster ones (scanner, printer) are connected to parallel ports. The keyboard and monitor are connected to specialized ports.
In order to avoid connecting a device to someone else’s port by mistake or ignorance, each device has an individual plug shape that does not fit into the “foreign” connector.
Information presented in digital form and processed on a computer is called data.
The sequence of commands that a computer executes while processing data is called program.
Processing data on a computer:
1. The user launches a program stored in long-term memory, it is loaded into operational memory and begins to execute.
2. Execution: The processor reads the instructions and executes them. The necessary data is loaded into RAM from long-term memory or entered using input devices.
3. The output (received) data is written by the processor into RAM or long-term memory, and is also provided to the user using information output devices.
To ensure information exchange between different devices, some kind of backbone must be provided to move information flows.
Trunk (system bus) includes three multi-bit buses: data bus, address bus and control bus, which are multi-wire lines. The processor and RAM, as well as peripheral input, output and information storage devices that exchange information in machine language (sequences of zeros and ones in the form of electrical pulses) are connected to the bus.
Data bus. This bus transfers data between different devices. For example, data read from RAM may be sent to the processor for processing, and then the received data may be sent back to RAM for storage. Thus, data on the data bus can be transferred from device to device in any direction, i.e. the data bus is bidirectional. The main operating modes of the processor using the data bus include the following: writing/reading data from RAM, writing/reading data from external memory, reading data from an input device, sending data to an output device.
The data bus width is determined by the processor bit capacity, that is, the number of binary bits that can be processed or transmitted by the processor simultaneously. The capacity of processors is constantly increasing as computer technology develops.
Address bus. The choice of device or memory cell to which data is sent or read via the data bus is made by the processor. Each device or RAM cell has its own address. The address is transmitted along the address bus, and signals are transmitted along it in one direction - from the processor to RAM and devices (unidirectional bus).
The width of the address bus determines the amount of addressable memory (address space), that is, the number of one-byte RAM cells that can have unique addresses.
The number of addressable memory cells can be calculated using the formula:
N=2 I, where I is the address bus width.
Each bus has its own address space, i.e. the maximum amount of addressable memory:
2 16 = 64 KB
2 20 = 1 MB
2 24 = 16 MB
2 32 = 4 GB
Control bus. The control bus transmits signals that determine the nature of information exchange along the highway. Control signals indicate what operation - reading or writing information from memory - needs to be performed, synchronize the exchange of information between devices, and so on.
Modular principle allows the consumer to assemble the computer configuration he needs and, if necessary, upgrade it. Each individual computer function is implemented by one or more modules - structurally and functionally complete electronic units in a standard design. Organizing a computer structure on a modular basis is similar to building a block house.
The backbone-modular principle has a number of advantages:
1. To work with external devices, the same processor commands are used as for working with memory.
2. Connecting additional devices to the backbone does not require changes to existing devices, processor, or memory.
3. By changing the composition of the modules, you can change the power and purpose of the computer during its operation.
3. Von Neumann's principles. Architecture of a classical computer, P von Neumann principles
The functioning of a computer is based on two fundamental concepts in computing. technology: concept of algorithm; principle of program control. An algorithm is a uniquely defined sequence of actions, consisting of formally defined operations on initial data, leading to a solution in a finite number of steps.
Properties algorithms
discreteness of information with which algorithms work; the finiteness and elementary nature of the set of operations performed when implementing the algorithm;
determinism - reproducibility of the results of the algorithm;
mass character - the possibility of using the algorithm for various initial data from an admissible set
A program is a description of an algorithm in any language.
Principle software management(PPU) was first formulated by the Hungarian mathematician and physicist John von Neumann, with the participation of Holtztein and Bertz in 1946, and is dominant at this stage in the development of computing technology.
PPU includes several architectural and functional principles.
1) Binary coding principle Information is encoded in binary form and divided into units (elements) of information called words. The use of the binary number system is determined by the specifics of electronic circuits. A word is an indivisible unit of information.
2) Uniformity of information coding. Different types of information words differ in the way they are used, but not in the way they are encoded. Words representing different types of information are indistinguishable (data, commands). The order in which they are used determines their specificity. The same commands can be used to process different data.
3) Address organization of RAM. Words of information are placed in machine memory cells and are identified by cell numbers called word addresses. Determines the specifics of storing and identifying information. The cell address is the machine identifier for the value and command.
4) The computer has a limited set of commands. Each individual command defines a simple (single) step of converting information.
5) The algorithm is implemented through sequential execution of commands. Performing calculations prescribed by the algorithm comes down to sequential execution of commands in an order uniquely determined by the program. The address of the next command is uniquely determined during the execution of the current command (conditional jumps are possible). The computation process continues until the command is executed to complete the computation. Advantages:
Ease of hardware implementation.
High versatility, which is limited only by the set of processor commands.
Flaws:
point 2: requires the programmer to correctly use data of various types; if they are not followed, errors appear that are often difficult to identify. When solving complex computing problems, this greatly increases the complexity of software development.
pz. assumes a linear organization of memory. This makes it difficult to calculate the layout elements of complex data types.
Classical architecturecomputer
Computer structure
In 1946, D. von Neumann, G. Goldstein and A. Berks, in their joint article, outlined new principles for the construction and operation of computers. Subsequently, the first two generations of computers were produced on the basis of these principles. There have been some changes in later generations, although Neumann's principles are still relevant today.
In fact, Neumann managed to summarize the scientific developments and discoveries of many other scientists and formulate something fundamentally new on their basis.
Von Neumann's principles
Use of the binary number system in computers.
The advantage over the decimal number system is that devices can be made quite simple, and arithmetic and logical operations in the binary number system are also performed quite simply. Computer software control
. The operation of the computer is controlled by a program consisting of a set of commands. Commands are executed sequentially one after another. The creation of a machine with a stored program was the beginning of what we call programming today.
Computer memory is used not only to store data, but also programs..
At any time, you can access any memory cell by its address. This principle opened up the possibility of using variables in programming. Possibility of conditional jump during program execution
.
Despite the fact that commands are executed sequentially, programs can implement the ability to jump to any section of code.
The most important consequence of these principles is that now the program was no longer a permanent part of the machine (like, for example, a calculator). It became possible to easily change the program. But the equipment, of course, remains unchanged and very simple.
By comparison, the program of the ENIAC computer (which did not have a stored program) was determined by special jumpers on the panel. It could take more than one day to reprogram the machine (set jumpers differently). And although programs for modern computers can take years to write, they work on millions of computers after a few minutes of installation on the hard drive.
How does a von Neumann machine work?
A von Neumann machine consists of a storage device (memory) - a memory, an arithmetic-logical unit - ALU, a control device - CU, as well as input and output devices.
Programs and data are entered into memory from the input device through an arithmetic logic unit. All program commands are written to adjacent memory cells, and data for processing can be contained in arbitrary cells. For any program, the last command must be the shutdown command.
The command consists of an indication of what operation should be performed (from the possible operations on a given hardware) and the addresses of memory cells where the data on which the specified operation should be performed is stored, as well as the address of the cell where the result should be written (if it needs to be saved in memory).
The arithmetic logic unit performs the operations specified by the instructions on the specified data.
The control device contains a special register (cell) called the “program counter”. After loading the program and data into memory, the address of the first instruction of the program is written to the program counter. The control unit reads from memory the contents of the memory cell, the address of which is in the program counter, and places it in a special device - the “Command Register”. The control unit determines the operation of the command, “marks” in memory the data whose addresses are specified in the command, and controls the execution of the command. The operation is performed by the ALU or computer hardware.
As a result of the execution of any command, the program counter changes by one and, therefore, points to the next command of the program. When it is necessary to execute a command that is not next in order to the current one, but is separated from the given one by a certain number of addresses, then a special jump command contains the address of the cell to which control must be transferred.
What achievements in computer science John von Neumann made in the twentieth century, you will learn from this article.
Before talking about his achievements in computer science, it is worth talking about the scientist’s first steps on the path of science. His first work, “Towards the Introduction of Transfinite Ordinal Numbers,” was published in 1923 at the University of Szeged, where he studied. In his doctoral dissertation he developed a system of axioms. In 1925, Neumann defended his dissertation on the topic “Axiomatic construction of set theory” at the University of Budapest and received a diploma in chemical engineering from the University of Zurich. In 1927 he became a privatdozent at the University of Berlin, and two years later at the University of Hamburg. In 1931 he received a professorship at Princeton University.
In 1943 - 1946, the first computer (electro-computer) was built, which was named ENIAC. John von Neumann suggested to its developers how to simplify the programming of the machine by modifying it. A in the creation of the second EDVAC machine - he already took an active part in the development of an electronic automatic computer with discrete variables. He was responsible for the development of a detailed logical diagram of the machine, in which idealized computational elements were structural units. These idealized elements became a step forward in computer science, as they made it possible to separate the logical circuit from its technical implementation.
John von Neumann proposed using an electrostatic memory system instead of a delay line as memory elements. The newly created machine was named JONIAC, in honor of Neumann.
The author’s scientific works are “On the foundations of quantum mechanics”, “Mathematical justification of quantum mechanics”, “Theoretical and probabilistic construction of quantum mechanics”, “Thermodynamics of quantum mechanical systems”, “Towards the Hilbert theory of proof”, “Towards the theory of strategic games”, “On the definition through transfinite induction and related issues of general set theory”, “On one problem of consistency of axiomatic set theory”.
Besides the fact that he participated in the creation of a computer, the scientist was the first to formulate the principles of computer operation. Principles formulated by John von Neumann:
In 1946, D. von Neumann, G. Goldstein and A. Berks, in their joint article, outlined new principles for the construction and operation of computers. Subsequently, the first two generations of computers were produced on the basis of these principles. There have been some changes in later generations, although Neumann's principles are still relevant today.
In fact, Neumann managed to summarize the scientific developments and discoveries of many other scientists and formulate something fundamentally new on their basis.
The most important consequence of these principles is that now the program was no longer a permanent part of the machine (like, for example, a calculator). It became possible to easily change the program. But the equipment, of course, remains unchanged and very simple.
By comparison, the program of the ENIAC computer (which did not have a stored program) was determined by special jumpers on the panel. It could take more than one day to reprogram the machine (set jumpers differently). And although programs for modern computers can take years to write, they work on millions of computers after a few minutes of installation on the hard drive.
A von Neumann machine consists of a storage device (memory) - a memory, an arithmetic-logical unit - ALU, a control device - CU, as well as input and output devices.
Programs and data are entered into memory from the input device through an arithmetic logic unit. All program commands are written to adjacent memory cells, and data for processing can be contained in arbitrary cells. For any program, the last command must be the shutdown command.
The command consists of an indication of what operation should be performed (from the possible operations on a given hardware) and the addresses of memory cells where the data on which the specified operation should be performed is stored, as well as the address of the cell where the result should be written (if it needs to be saved in memory).
The arithmetic logic unit performs the operations specified by the instructions on the specified data.
From the arithmetic logic unit, the results are output to memory or an output device. The fundamental difference between a memory and an output device is that in a memory, data is stored in a form convenient for processing by a computer, and it is sent to output devices (printer, monitor, etc.) in a way that is convenient for a person.
The control unit controls all parts of the computer. From the control device, other devices receive signals “what to do”, and from other devices the control unit receives information about their status.
The control device contains a special register (cell) called the “program counter”. After loading the program and data into memory, the address of the first instruction of the program is written to the program counter. The control unit reads from memory the contents of the memory cell, the address of which is in the program counter, and places it in a special device - the “Command Register”. The control unit determines the operation of the command, “marks” in memory the data whose addresses are specified in the command, and controls the execution of the command. The operation is performed by the ALU or computer hardware.
As a result of the execution of any command, the program counter changes by one and, therefore, points to the next command of the program. When it is necessary to execute a command that is not next in order to the current one, but is separated from the given one by a certain number of addresses, then a special jump command contains the address of the cell to which control must be transferred.
