Essay

CONNECTING DEVICE, ISA SYSTEM BUS, PULSE RATE METER, ADDRESS SELECTOR, INTERNAL STROBE GENERATION UNIT

The purpose of the work is to develop an interface device for a personal computer such as IBM PC using the ISA interface. The interface device is designed to receive information from a computer, process this information according to a given algorithm, and output the result of information processing to the computer.

During the work, an interface device was designed that was connected to the ISA system bus. The interface device performs the function of measuring the pulse repetition rate. Simulation of this function was carried out in the Electronics Workbench program.

As a result of the work, a functional diagram was designed, circuit diagram, as well as the operating part.

Introduction

1. Description of the operating algorithm of the control system

2. Description of the functional diagram of the control system

2.2 Description of the operation of the functional diagram of the operating part of the control system

3. Description of the circuit diagram

4. Modeling the OPUS circuit in EWB

5. Diagram of operation of the interface device

Conclusion

List of sources used

Appendix A. Mandatory. Algorithm for the operation of the system

Appendix B. Mandatory. PGU 3.090105.002 E2 Interface device. Functional diagram of the interface part

Appendix B. Mandatory. PGU 3.090105.003 E2 Interface device. Functional diagram of the operating part

Appendix D. Mandatory. PGU 3.090105.004 E3 Interface device. Electrical circuit diagram

Appendix D. Mandatory. PGU 3.090105.004 PE3 Interface device. List of elements

Introduction

Devices that allow the computer to receive information from external sources are called interface devices. To connect them, expansion buses are provided on the motherboard. The use of a computer to monitor the state of any external physical processes is obvious - the equipment is tasked with adapting the signal from the source for processing by a program, and the computer is responsible for logical processing of the received information.

In this course project, it is necessary to design a control system that allows you to measure the repetition rate of rectangular pulses from an external source.

Interface devices can be connected to a personal computer such as an IBM PC in three ways, corresponding to three types of standard external interfaces, the tools of which are included in the basic configuration of the computer:

Via the system backbone or bus (this is ISA (Industrial Standard Architecture), EISA (Extended ISA), PCI (Peripheral Component Interconnect), VLB (Video Local Bus) or VESA (Video Electronics Standards Association), PCMCIA (Personal Computer Memory Card International Association );

Via Centronics parallel interface;

Via serial interface RS-232C.

Each of the three connection methods indicated has its own advantages and disadvantages. For this project, a connection to the ISA system bus was chosen as an input/output device

Description of the operating algorithm of the US

The interface device (US) receives information from the computer, processes the information according to a given algorithm, and outputs the result of information processing to the computer.

The operating system functionally consists of two parts: interface and operational. In accordance with the assignment option, during the design of the control system, sixteen-bit exchange via the ISA bus was used. This data bus width requires the use of one address accessible for writing and reading and one address for the ready flag. In accordance with these requirements, the following algorithm for the functioning of the control system was developed:

1. Formation of the US address code and the –IOW signal on the ISA bus.

3. Formation of a recording strobe at the selected address by the Internal Strobe Generation Unit (ISG) and recording of the low-order part of the number M=2 14 into the subtractive counter. Reset the totalizer.

4. Reception of a pulse of the measured frequency.

5. Decrease the value of subtractive counters. Increasing the value of the summing counters.

6. If the value of the subtracting counters is not zero, then go to step 4.

7. Setting the ready flag.

8. Formation of the US address code and the –IOR signal to the ISA bus.

10.Setting the number N on the ISA bus data bus.

11. Setting the high address of the US and the –IOR signal to the ISA bus.

13. Putting the high part of the number N on the ISA bus data bus.

The function of calculating the measured frequency is implemented in software. During the counting cycle, the program polls the readiness flag and, upon its change, requests the output of the result. The frequency is calculated using the formula:

–N – number obtained as a result of measurement;

–F 0 – clock generator frequency;

–F – desired frequency;

–M – number set on the clock pulse counter, i.e. the size of the time window of the measurement cycle

2. Description of the functional diagram

The functional diagram of the interface part of the control system is presented in Appendix B.

2.1 Description of the operation of the functional diagram of the interface part of the control system

The functional diagram of the interface part of the control system contains the following elements:

1. input and output buffers;

2. address selector;

3. block for generating internal gates;

4. block for implementing asynchronous exchange;

Buffering of trunk signals is used for electrical matching and performs two main functions: electrical isolation (for all signals) and transmission of signals in the desired direction (bidirectional signals only). This is the first and most obvious interface function of any US system. Buffering is the first and most obvious interface function of any control system. Sometimes, with the help of buffering, multiplexing of signals is also implemented, which is necessary according to the task. The most commonly used chips are trunk receivers, transmitters, and transceivers, often also called buffers.

Transceiver requirements include the requirements for receivers and transmitters, i.e. low input current, high output current, high speed and mandatory output shutdown. For a large number of discharges, it is necessary to use special transceiver microcircuits. These ICs come in two basic types: two bidirectional buses or three buses (one bidirectional, one input, and one output). Two control signals are used to control the operation of the transceivers. Note that if open-collector transceivers are used to buffer the data bus, then at their outputs it is necessary to include resistors on the +5V bus (if they do not work on the line to which these resistors are already connected).

The second main interface function performed by US operating in software exchange mode is address decryption. This function is performed by an address selector (SA), which must generate signals corresponding to the setting on the bus address bus of an address code belonging to a given device, or one of the address zones of a given device. In this course project, the SA was built at address 0x36C for read-write and at the ready flag address 0x36D. In this term paper CA was implemented using code comparator (CC) chips.

The internal strobes generation unit generates internal strobes for writing and reading at specified addresses synchronously with the –IOW and –IOR signals received from the ISA bus.

The main method of exchange over the ISA backbone is synchronous. At this type the exchange does not take into account the performance of the performer. If the performance of the performer is low, there is a possibility that the data transfer will be incorrect. To eliminate the possibility of erroneous data transmission, asynchronous exchange is used by removing the –I/O CH RDY signal from the signal issued by the US. Asynchronous exchange is provided by the DK block.

The interface part of the control system works as follows. From ISA, the input buffers receive address 0x36C, signal –IOW, data – number M=2 14. After passing through the buffer part, the address code is sent to the CA. After SA, the signal arrives at the BVVS, synchronously with the –IOW signal. Also, the signal from the CA is sent to the ISA bus to generate the I/O CS 16 signal, to determine that the CS is accessed in sixteen-bit mode. Next, the BVVS generates a strobe, which goes to the operational part, producing parallel loading of subtractive counters and reset of adding counters, and to the control input of the data bus multiplexer, ensuring data transfer in the desired direction. After the measurement cycle, the ready flag is read, which sends the –I/O CH RDY signal to the ISA bus if the ready flag is set. After this, a cycle of reading work is carried out. The address is set and decrypted, a reading strobe is generated, the data bus multiplexer is set to transmit in the other direction, and the number code N is installed on the data bus.

The first full-fledged personal computer is considered to be the Apple II, released in June 1977. However, back in 1973, Xerox released the Xerox Alto personal computer, which had a THREE-BUTTON OPTICAL mouse! In addition, the computer's arsenal included a network card and a graphical user interface. Such a “luxury” became available to most users only after 10-17 years. The Xerox Alto itself never went on general sale.

And in December 1974, the first computer affordable for everyone was the Altair 8800. This device was created on the basis of the new 8-bit Intel-8080 processor. CP/M was used as the operating system.

In 1975, Bill Gates and his colleague Paul Allen decided to write a BASIC language interpreter for the Altair 8800 computer and together founded the Micro-Soft company. The main specialization of the newly formed company was the development of computer software.

A year later, on April 1, 1976, Steve Jobs and Steve Wozniak founded Apple company Computer, known for its Apple Macintosh series computers and other developments.

As personal computers became available More and more people have seen growth in the software development industry. As a result, the wide variety of software developed significantly accelerated the further spread and use of PCs in society.

In the late seventies, an increase in demand for personal computers led to a decrease in demand for mainframe and minicomputers. The business world has realized that it is more profitable to buy computers than electronic computers. This turn of events caused serious concern at IBM, which was the leading computer company at the time.

And so, in 1979, the bosses from IBM decided that, as an experiment, they should try their hand at the market personal computers. At this time, about ten computer manufacturing companies were already active in the PC market. In this regard, IBM decided not to waste time and large amounts of money developing its own product from scratch.

One of the IBM departments that was responsible for this experiment was allowed to use components made by other companies. And as the main processor, the developers decided to use the latest 16-bit micro Intel processor 8088.

Remarkably, that the software was entrusted to be developed by a small company called Microsoft, founded by Bill Gates 4 years before this event...

August 1981 came... IBM officially presented to the public its new personal computer called the IBM PC. Users appreciated the new development and the IBM PC quickly gained great popularity and after a couple of years the IBM PC became the standard for a personal computer.

The reason for the tremendous success of the IBM PC is explained by the possibility of improving individual parts of the computer and using fundamentally new devices. Both then and now, you can assemble a computer from independently manufactured parts, similar to a children's construction set.

Huge popularity The IBM PC contributed to the massive emergence of PC-compatible clones. The era of personal computers and the computer revolution has arrived.

In 1986, IBM could no longer maintain its leading position in the IBM PC-compatible computer market, and in 2004 the company officially announced the sale of personal computer production to Lenovo, itself to a large manufacturer computers in China...

Typically, IBM PC personal computers consist of the following parts (blocks):
- system block(in vertical or horizontal version);
- monitor(display) for displaying text and graphic information;
- keyboards, which allows you to enter various characters into the computer.
The most important unit in a computer is the system unit; it contains all the main components of the computer. The PC system unit contains a number of basic technical devices, the main ones of which are: microprocessor, random access memory, read-only memory, power supply and I/O ports, drives.
In addition, the following devices can be connected to the PC system unit:
- Printer for printing text and graphic information;
- mouse-type manipulator- a device that controls the graphic cursor
- joystick, used primarily in computer games;
- plotter or plotter- a device for printing drawings on paper;
- scanner- a device for reading graphic and text information;
- CD-ROM- CD reader, used to play moving images, text and sound;
- modem- a device for exchanging information with other computers via telephone network;
- streamer- a device for storing data on magnetic tape;
- network adapter - a device that allows a computer to work local network.
The main components of a personal computer are the following devices: processor, memory (RAM and external), devices for connecting terminals and data transmission. Here is a description of the various devices included in the computer or connected to it.
Microprocessor
A microprocessor is a large integrated circuit (LSI) made on a single chip, which is an element for creating computers of various types and purposes. It can be programmed to perform an arbitrary logical function, meaning that by changing programs, the microprocessor can be forced to be part of an arithmetic unit or to control input/output. Memory and input/output devices can be connected to the microprocessor.
IBM PC computers use Intel microprocessors, as well as compatible microprocessors from other companies.
Microprocessors differ from each other in type (model) and clock frequency (the speed of performing elementary operations, given in megahertz - MHz). The most common models from Intel are: 8088, 80286, 80386SX, 80386DX, 80486, Pentium and Pentium-Pro, Pentium-II, Pentium-III, they are listed in order of increasing performance and price. Identical models may have different clock frequencies - the higher clock frequency, the higher the performance and price.
The main Intel 8088, 80286, 80386 microprocessors released earlier do not contain special commands for processing floating point numbers, therefore, to increase their performance, so-called mathematical coprocessors can be installed that increase performance when processing floating point numbers.
Memory
Random Access Memory or RAM(RAM - OP), as well as read-only memory (ROM - ROM) form internal memory computer to which the microprocessor has direct access during its operation. Any information during processing is first rewritten by the computer from external memory (from magnetic disks) into RAM. The OP contains data and programs being processed at the current moment of computer operation. Information in the OP is received (copied) from external memory and, after processing, written there again. Information in the OP is contained only during a work session and is irretrievably lost when the PC is turned off or there is an emergency power failure. In this regard, the user must regularly write information that is subject to long-term storage from the OP onto magnetic disks during operation in order to avoid its loss.
The larger the RAM volume, the higher the computing power of the computer. As you know, to determine the amount of information, a unit of measurement is used: 1 byte, which is a combination of eight bits (zeros and ones). In these units of measurement, the amount of information stored in the OP or on a floppy disk can be written as 360kb, 720kb or 1.2Mb. Here 1Kb = 1024 bytes, and 1MB (1 megabyte is 1,024Kb, while a hard drive can accommodate 500MB, 1000MB or more.
For IBM PC XT volume OH. as a rule, it is 640kb, for IBM PC AT - more than 1 MB, for older IBM PC models - from 1 to 8 MB, but it can be 16, 32 MB and even more - the memory can be expanded by adding microcircuits on the main board of the computer.
Unlike OP, ROM constantly stores the same information, and the user cannot change it, although he has the ability to read it. Typically, the ROM volume is small and ranges from 32 to 64 KB. ROM stores various programs that are written at the factory and are primarily intended to initialize the computer when it is turned on.
RAM with a capacity of 1 MB usually consists of two parts: the first 640 KB can be used by the application program and operating system(OS). The rest of the memory is used for service purposes:
- to store a part of the OS that provides testing of the computer, bootstrap OS, as well as performing basic low-level input and output services;
- to transfer images to the screen;
- for storing various OS extensions that appear along with additional computer devices.
As a rule, when talking about the amount of memory (RAM), they mean the first part of it, and it is sometimes insufficient to run some programs.
This problem is resolved using extended and expanded memory.
Intel microprocessors 80286, 80386SX and 80486SX can handle larger RAM sizes - 16 MB, and 80386 and 80486 - 4 GB, but MS DOS cannot directly work with RAM larger than 640 KB. To access additional OP, developed special programs(drivers) that allow receiving a request from an application program and switching to the “protected mode” of the microprocessor. Having completed the request, the drivers switch to the normal operating mode of the microprocessor.
Cash
Cache is a special high-speed processor memory. It is used as a buffer to speed up the work of the processor with the OP. In addition to the processor, the PC contains:
- electronic circuits(controllers) that control the operation of various devices included in the computer (monitor, drives, etc.);
- input and output ports through which the processor exchanges data with external devices. There are specialized ports through which data is exchanged with the internal devices of the computer, and general-purpose ports to which various additional external devices (printer, mouse, etc.) can be connected.
General purpose ports come in two types: parallel, designated LPT1 - LPT9, and asynchronous serial, designated COM1 - COM4. Parallel ports perform input and output faster than serial ports, but also require more wires for data exchange (the port for the domain with the printer is parallel, and the port for exchange with the modem via the telephone network is serial).
Graphics adapters
Monitor or display is required peripheral device The PC is used to display processed information from the computer's RAM.
Based on the number of colors used when presenting information on the screen, displays are divided into monochrome and color, and based on the type of information displayed on the screen - into symbolic (only symbolic information is displayed) and graphic (both symbolic and graphic information is displayed). A video computer consists of two parts: a monitor and an adapter. We only see the monitor, the adapter is hidden in the body of the machine. The monitor itself contains only a cathode ray tube. The adapter contains logic circuits that output a video signal. The electron beam travels through the screen in about 1/50th of a second, but the image changes quite rarely. Therefore, the video signal entering the screen must again generate (regenerate) the same image. To store it, the adapter has video memory.
In character mode, the display screen, as a rule, simultaneously displays 25 lines of 80 characters per line (a total of 2000 characters - the number of characters on a standard typewritten sheet), and in graphic mode, the screen resolution is determined by the characteristics of the monitor adapter board - the device for connecting it to the system unit .
The quality of the image on the monitor screen depends on the type of graphics adapter used.
The most widely used adapters are the following types: EGA, VGA and SVGA. Currently, VGA and SVGA (SuperVGA) are quite widely used. SVGA has a very high resolution. Previously, a CGA adapter was used, but it is no longer used on modern computers.
Adapters vary" resolution" (for graphic modes). Resolution is measured by the number of lines and the number of elements per line ("pixel"), in other words, dots per line. For example, a monitor with a resolution of 720x348 displays vertical 348 lines of dots, 720 dots per line. For Publishing systems use monitors with resolutions of 800x600 and 1024x768.Such monitors are very expensive.
Screens come in standard size (14 inches), enlarged (15 inches) and large like a TV (17, 20 and even 21 inches - i.e. 54 cm diagonally), color (from 16 to several tens of millions of colors) and monochrome.
The monitor adapter standard also determines the number of colors in the palette of color monitors: CGA in graphic mode has 4 colors, EGA has 64 colors, VGA has up to 256 colors, and SVGA has more than a million colors. In text mode, all of the listed standards allow you to reproduce 16 colors.
The choice of one type of monitor or another depends on the type of problem being solved on a PC. For example, if the user processes only textual information, then a monochrome character monitor will be sufficient for him, but if he solves problems (computer-aided design), then he needs a color graphic monitor. However, for most applications, color graphic monitors and adapters are preferable.
Disk drives
Information storage devices - an integral part of any computer - are often called external storage media or external computer memory. They are designed for long-term storage of voluminous information, while their contents do not depend on the current state of the PC. On external media Any data and programs are stored, so a library of user data is formed and stored here.
Information storage devices in personal computers are magnetic disk drives(NMD), in which direct access to information is organized. Recently, for PCs there have appeared magnetic tape drives- streamers that can contain very large amounts of information, but at the same time organize only sequential access to it. However, streamers do not replace magnetic disk drives, but only complement them. There are enough NMDs: floppy magnetic disk drives (FMD) and hard magnetic disk drives (HDD).
Hard disk drives are designed for permanent storage of information. On an IBM PC with an 80286 microprocessor, usually hard capacity disk size ranges from 20 to 40 MB, with 80386 SX, DX and 80486SX - up to 300 MB, with 804S6DX up to 500-600 MB, with PENTIUM - more than 2 GB.
The hard drive is a non-removable magnetic disk that is protected by a hermetically sealed case and is located inside the system unit. It may consist of several disks having two magnetic surfaces combined into one package.
A hard drive, unlike a floppy disk, allows you to store large amounts of information, which provides greater opportunities for the user.
When working with a hard disk drive, the user must know how much memory is occupied by data and programs stored on disks, how much free memory is available, control the filling of memory and rationally place information in it. The most common floppy disk sizes are 5.25 and 3.5 inches.
Floppy disk drives (FHD) allow you to transfer information from one computer to another, store information that is not constantly used on the computer, and make archival copies of information stored on the hard drive. A floppy disk (floppy disk) is a thin disk made of a special material with a magnetic coating applied to its surface. On the plastic body of the floppy disk there is a rectangular slot for recording protection, a hole for contact of the magnetic disk with the read heads of the disk drive, and a label with the parameters of the floppy disk.
The main parameter of a floppy disk is its diameter. Currently, there are two main standards for floppy disk drives - floppy disks with a diameter of 3.5 and 5.25 inches (89 and 133 mm, respectively). As a rule, IBM PC XT and IBM PC AT mainly use floppy disks with a diameter of 5.25 inches, and older IBM PC models use floppy disks with a diameter of 3.5 inches.
To write and read information, the floppy disk is installed in the drive slot, which is located in system unit. A PC may have one or two disk drives. Since a floppy disk is a removable device, it is used not only to store information, but also to transfer information from one PC to another.
5.25-inch floppy disks, depending on the quality of production, can contain information of 360, 720 KB or 1.2 MB.
You can determine the maximum capacity of 3.5-inch floppy disks by their appearance: floppy disks with a capacity of 1.44 MB have a special slot in the lower right corner, but floppy disks with a capacity of 720 KB do not. These floppy disks are enclosed in a hard plastic case, which significantly increases their reliability and durability. In this regard, on new computers, 3.5-inch floppy disks are replacing 5.25-inch floppy disks.
Write protection of floppy disks. 5.25" floppy disks have a write-protection slot. If this slot is sealed, it will be impossible to write to the floppy disk. On 3.5-inch floppy disks, there are write-protection slots and a special switch - a latch that allows or prohibits writing to the floppy disk. Recording permission mode - the hole is closed, if the hole is open, then recording is prohibited.
Initializing (formatting) floppy disks. Before using it for the first time, the floppy disk must be initialized (marked) in a special way.
In addition to conventional disk drives, modern computers have special disk drives for laser compact discs (CD-ROM), as well as for magnetic-optical disks and Bernoulli disks.
CD-ROM - compact discs, many large software packages for modern computers are produced on such disks. CD - ROM drives differ in information transfer speed - regular, double, quadruple, etc. speed. Modern 24 - 36 - speed disk drives operate almost at the speed of a hard drive.
A typical CD has a capacity of more than 600 MB or 600 million characters, but it is intended only for playback and does not allow recording. Rewritable CDs and corresponding drives are already available, but they are very expensive. Currently, sets of excellent quality photographs, discs with video clips and films are sold on CDs. Sets of games with a variety of music and sound effects, computer encyclopedias, educational programs - all of this is released only on CD.
Printers and plotters
A printer (printing device) is designed to output text and graphic information from the computer's RAM onto paper, and the paper can be either sheet or roll.
The main advantage of printers is the ability to use a large number of fonts, which allows you to create quite complex documents. Fonts differ in the width and height of letters, their inclination, and the distances between letters and lines.
To work with the printer, the user must select the font he needs and set print parameters to match the width of the output document and the size of the paper used. Based on this, for example, dot matrix printers have two modifications: printers with a narrow carriage (the width of a standard typewritten sheet) and printers with a wide carriage (the width of a standard typewritten sheet).
It must be remembered that the size of the “computer sheet” (the space allocated to the user’s PC for filling with symbolic information) significantly exceeds the size of the monitor screen and amounts to hundreds of columns and thousands of lines, which is determined by the amount of free RAM of the computer and the used software. When outputting information to a printer, the contents of the entire computer sheet are printed, and not just the part visible on the monitor screen. Therefore, it is first necessary to divide the text prepared for printing into pages, setting the required text width based on the type of font and the width of the paper.
Printers can output graphic information and even in color. There are hundreds of printer models. They can be of the following types: matrix, inkjet, lettered, laser.
Until recently, the most commonly used printers were dot matrix printers, the print head of which contains a vertical row of thin metal rods (needles). The head moves along the printed line, and the rods strike the paper at the right moment through the ink ribbon. This ensures the formation of an image on paper. Cheap printers use 9 pin heads and the print quality is quite mediocre, which can be improved with a few passes. Printers with 24 or 48 cores have higher quality and sufficient printing speed. Printing speed - from 10 to 60 seconds per page. When choosing a printer, people are usually interested in the ability to print Russian and Kazakh letters. In this case it is possible:
- fonts of Kazakh and Russian letters can be built into the printer. In this case, after turning on the printer is immediately ready to print texts in Kazakh and Russian. If the codes of Kazakh and Russian letters are the same as in the computer, then the texts can be printed using the DOS PRINT or COPY commands. If the codes do not match, then you have to use transcoding drivers.
- fonts of Kazakh and Russian letters are missing in the printer ROM. Then, before printing texts, you need to download the letter font loading driver. When the printer is turned off, they disappear from memory.
Dot matrix printers easy to operate, have the lowest cost, but rather low productivity and print quality, especially when outputting graphic data.
Inkjet printers The image is formed by micro drops of special ink. They are more expensive than dot matrix printers and require careful maintenance. They operate silently, have a lot of built-in fonts, but are very sensitive to paper quality - The quality and productivity of inkjet printers is higher than that of dot matrix printers. Some of the disadvantages are: fairly high ink consumption and moisture instability of printed documents.
Laser printers provide the best print quality, using the principle of xerography - the image is transferred to paper from a special drum to which ink particles are electrically attracted. The difference from a xerographic machine is that the printing drum is electrified using a laser beam according to commands from the machine. The resolution of these printers is from 300 to 1200 dpi. Printing speed is from 3 to 15 seconds per page when outputting text. Laser printers offer the best print quality and performance, but are the most expensive of the printer types reviewed.
Plotter(plotter) also serves to display information on paper and is mainly used to display graphic information. Plot plotters are widely used in design automation, when it is necessary to obtain drawings of products being developed. Plotters are divided into single-color and color, and also according to the quality of information output when printed.
Computer input devices
Keyboard - The main device for entering information into the computer is still the keyboard; you can use it to enter text information and give commands to the computer. We will learn more about the keyboard functionality in the next lesson.
Mouse together with the keyboard is intended to control the computer. This is separate small device with two or three buttons, which the user moves along the horizontal surface of the desktop, pressing the appropriate keys if necessary to perform certain operations.
Scanner allows you to enter any type of information into a computer from a sheet of paper, and the entry procedure is simple, convenient and quite fast.
Additional devices
Modems(modulator-demodulator) are used to transfer data between computers and they differ mainly in the speed of information transfer. Modem speeds today vary from 2400 bits/sec to 25,000 thousand bits/sec. They support certain standards of data exchange procedures (protocols). When connecting to some kind of computer network (InterNet, Relcom, FidoNet, etc.) or to use Email A modem is the most necessary device.
There are also fax modems that combine the functions of a modem with a fax machine. Using a fax modem, you can send text information not only to your subscriber’s computer, but also to a simple fax machine and, accordingly, receive it. Fax modems are somewhat more expensive than modems, but their capabilities are wider.
Nowadays they often talk about the multimedia capabilities of computers. Multimedia is a modern method of displaying information based on the use of text, graphic and sound capabilities of a computer, i.e. it is the combined use of image, sound, text, music and animation to better display data on the screen. A computer with such capabilities must have a sound card and a CD-ROM drive that can reproduce colors, soundtracks and videos from a regular CD. Multimedia computers may also contain a special video card for connecting a video camera, VCR and television signal receiving device.

Control questions

1. List the main PC components and additional devices.
2. What printers are used when running a PC?
3. What video adapters do you know? What is the difference between a display and a video adapter?
4. What floppy disks are used on your computer?
5. What is a modem and what is it used for?

We all use personal computers and take them for granted in our daily lives. It's easy to forget that computers have only been around us for the last few decades, and the first ones were much larger than the ones on our desks today.

Did you know that the first laptop computer weighed 25 kg and cost about $20,000, that the first laser printer was so large that it filled most of the room, or that buyers of the first personal computers had to assemble them themselves? This article will give you a look at some of the first prototypes of computer hardware and what they looked like.

The first computer mouse

The first computer mouse was invented in 1963 by Douglas Engelbart at the Stanford Research Institute. He is also one of the inventors of hypertext. The first mouse used two wheels positioned at 90 degrees to each other to track movement along 2 axes. However, this design had many disadvantages, and soon the 2 wheels were replaced with a ball. The ball mouse was invented in 1972, and optical mouse was invented around 1980, although this design became popular much later. Douglas Engelbart received no royalties for his invention and his patent expired before computer mice became commonplace in the personal computer era.

First mouse. On the right you can see the wheels that are used for movement and positioning.

First trackball

In fact, the trackball was designed 11 years before the invention of the first computer mouse. It was invented by Tom Cranston and Fred Longstaff in 1952 as part of the DATAR automated information warfare system, an initiative of the Canadian Navy. The design used a 5-pin bowling ball, which is slightly smaller than a standard 10-pin bowling ball.

First trackball: bowling ball and that's it.

First laptop computer

This computer was supposed to be a "mobile" computer. The IBM 5100 Portable Computer was created in 1975. It weighed 25 kg, was the size of a small suitcase and required an external power source. The block contained everything necessary: ​​a processor, several hundred kilobytes of non-volatile memory, 16-64 KB of RAM, a 5-inch CRT display, a keyboard and a tape drive. This computer was an incredible feat for its time. It also came with built-in BASIC and/or APL. Various IBM 5100 models cost between $8,975 and $19,975.

IBM 5100 Portable Computer.

First laptop

The first laptop was the Grid Compass 1100 (called GRiD), designed in 1979 by British industrial designer Bill Moggridge. The computer went on sale in 1982. It was produced with a screen resolution of 320 x 200, an 8086 processor, 340 KB of magnetic-electronic memory (this type of memory is now obsolete), and a 1.2 Kbit modem. The laptop weighed 5 kg and cost $8,000 – 10,000. GRiD was mainly used by NASA and the US military.

Grid Compass 1100 close-up.

IBM's first personal computer

The first IBM personal computer was introduced in 1981, the IBM 5150. The platform became so widespread in the 1980s that the term “personal computer” meant an IBM personal computer.

The IBM 5150 development project was called "Project Chess" and was worked on by a team of 12 people led by Don Estridge and Larry Potter. To speed up development and reduce costs, IBM decided to use off-the-shelf parts rather than construct new ones, as it traditionally did.

The first IBM PC had an Intel 8088 processor, 64 KB of RAM (expandable up to 256 KB), a floppy drive (from which MS-DOS could be loaded), and finally a CGA or monochrome video adapter. The machine also contained Microsoft BASIC in ROM. On the first IBM PC it could be optionally installed HDD by 10 MB, but only if the original power supply was replaced with a more powerful one.

The first personal computer, IBM PC 5160.

First Apple computer

The first Apple personal computers were designed and hand-built by Steve Wozniak. The Apple I went on sale in 1976 for $666.66. A total of 200 copies were produced. The Apple I basically just had a motherboard with a processor, 8KB of RAM, a display interface, and some additional functions. To get a fully working computer, the buyer must add a power supply, keyboard and display (and, of course, mount it all).

Apple I computer. On the left is the one already assembled by the user, and on the right is the form in which it could be purchased.

First RAM

The first rewritable random access memory was magnetic core memory (also called ferrite memory). It was invented in 1951 as a result of work done by An Wang at the Harvard University Computing Laboratory and Jay Forrester at the Massachusetts Institute of Technology.

Back then, random access memory used the magnetic properties of materials to give them the functionality that transistors had. Information was stored using the polarity of tiny magnetic ceramic rings through which wires passed. Unlike modern memory, this RAM could retain information even after the power was turned off.

This technology was standard until it was replaced by silicon integrated circuits in the 1970s.

Memory on magnetic cores.

First hard drive

IBM 350 Disk File became the first hard drive, which was part of the IBM 305 RAMAC computer, which began shipping in 1956 (the computer was intended for accounting). The hard drive had fifty 24-inch disks that together could store 4.4 MB of data. The 350 had a rotation speed of 1200 rpm, a data rate of 8800 characters per second and an access time of about 1 second.

The first IBM 350 Disk File hard drive.

First laser printer

The laser printer was invented by Harry Starkweather at XEROX in 1969. The first prototype was a modified copier where he removed the imaging system and introduced a rotating drum with 8 mirrored edges. First commercial implementation laser printer did not occur until IBM released the IBM 3800 laser printer model in 1976. The printer was so large that it could take up most of the room.

IBM 3800, the first commercial laser printer.

First web server

Since the Internet is an integral part of the modern world, it is impossible not to talk about the first web server. The first web server was the NeXT workstation that Tim Berners-Lee used when he invented the World Wide Web at CERN. The first web page became available online on August 6, 1991.

There was a sign on the computer that read: “This machine is a server. DO NOT TURN OFF!!". By turning it off, you could turn off the entire Internet.

The first web server and the famous inscription.

It's amazing how much has happened in the computer industry in just a few decades. Now just imagine what will happen in 30-40 years...

Translation of the article “The history of PC hardware, in pictures”

How Yandex uses your data and machine learning to personalize services -.

The most famous foreign PCs are IBM PC models of various generations and classes (Table 1).

The main branches of development of IBM PCs, within the framework of which modifications of PC models were carried out, mainly associated with an increase in the capacity of RAM, floppy disk drives and non-displacement disk drives, are given in Table. 2, and the characteristics of the IBM PC/XT/AT models are in table. 3.

Table 1. Stages of development of IBM PC models.

Model	Generation	Years of production
IBM PC	I	1981-1985
IBM PC/XT	I	1983-1986
IBM PCjr	I	1983-1985
IBM PC 3270	I	1983-1986
IBM PC/AT	II	1984-1988
IBM PC/370 AT	II	1985-1988
IBM PC/3270 AT	II	1986-1989
IBM Portable	II	1984
IBM Convertible	II	1986

Table 2. Development of IBM PC/XT/AT models from IBM.

Model	RAM, KB	NGDM, Kbyte	NMD, MB
IBM PC	256	1x360	-
IBM PC	256	2x360	-
IBM PC/XT	256	1x360	-
IBM PC/XT	256	2x360	-
IBM PC/XT	256	1x360	10
IBM PC/AT	512	1x360	20
IBM PC/AT	512	1x360	30

IBM PC is the first personal computer of the company, the basic model of which has a CPU, RAM with a capacity of 64 KB, which can be expanded to 640 KB, one or two float drives, ROM for storing system software (diagnostic program and BASIC language interpreter), monitor (usually monochrome), 5 I/O ports for various functional expansions. In the basic model, an external NMD with a capacity of 10 MB can be connected via the controller. A printer, plotter, and communication tools can be connected to the IBM PC using appropriate controllers.

IBM PC/XT, unlike the IBM PC, includes a hard disk drive (10 MB) built into the system unit, RAM with a capacity of 128 KB expandable to 640 KB, and 8 ports for configuration expansion. It is possible to add a second flexural motor and a rigid flexural motor to the model.

IBM PC/AT is available in two modifications. The base model includes 256 KB of RAM and a 1.2 MB HDD. The extended version contains RAM with a capacity of 512 KB, a 1.2 MB HDD, a 20 MB HDD, and 7 expansion slots. The operational memory is collected in separate 128 KB modules and can be expanded up to 3 MB. An MP 80287 can be used as a coprocessor. In the extended model, you can install an additional 20 MB NMD, as well as a 2X720 KB NMD.

IBM PC XT/370 - a combined version of the IBM PC/XT with three additional expansion cards that provide emulation of the IBM 3277 system terminal with computing resources, command system and OS of the IBM 370 system. In the IBM PC/XT operating mode, all the characteristics of a similar model are preserved.

Extension interfaces:

• the first installation location is an adapter for display/printer, color display;
• 2nd-8th places - 3277 terminal emulation boards, 370 system RAM boards, 370 system processor boards, additional NMD boards, HDMD boards and two synchronous type adapters.

The IBM PC XT/370 model works with all programming languages ​​running the virtual OS of the IBM 370 system. In the IBM PC/XT operating mode, all the characteristics of a similar model are preserved.

Extension interfaces:

• the first installation location is an adapter for display/printer, color display;
• 2nd - 8th places - 3277 terminal emulation boards, 370 system RAM boards, 370 system processor boards, additional NMD boards, HDMD boards and two synchronous type adapters.

Table 3. Development of IBM PC/XT/AT models from IBM.

Characteristic	IBM PC	IBM PC/XT	IBM PC/AT
Microprocessor type	8088	8088	80286
Clock frequency, MHz	4,77	4,77/8	6/8
RAM volume, KB	640	128...640	256...3000
Coprocessor type	8087	8087	80287
NGMD, diameter mm	133	133	133
Capacity of float drive, Kbyte	360	360	1200
NMD capacity, MB	-	20	20...40
Display type, M/C*	M	M/C	M/C
Screen capacity, characters	25x80	25x80	25x80
Graphic mode, dots	640x200	640x200	640x200/640x350
Total number of keys	83	83	84; 101/102
Number of function keys	10	10	10
System backbone	PC/XT bus	PC/XT bus	AT bus
Number of connectors for connecting to the trunk	1	1	2
Number of expansion slots:
8-bit	5	8	2
16-bit	-	-	6
Types of PU interfaces	RS-232C, Centronics	RS-232C, Centronics	RS-232C, Centronics
OS	PC DOS, MS DOS, CP/M-86	PC DOS, MS DOS, CP/M-86	PC DOS 3.0, MS DOS 3.0, XENIX
* M - monochrome, C - color

The IBM PC XT/370 model works with all programming languages ​​running the virtual OS of the IBM 370 system.

Among other IBM PC models, the portable IBM PC Convertable should be noted.

There are a large number of PCs compatible with IBM PC/XT/AT models (more than 300 companies). These models, as a rule, have better technical performance, advanced hardware configurations, and are cheaper. This is explained by the high pace of progress (change of model brands on average every two years), as well as the greater flexibility of small companies for technical innovations. Basically, the models of these companies are licensed and do not depend on IBM models.

Among the many companies that ensure compatibility of their models with IBM models, the most famous are traditional computer suppliers: Compaq Computer, Olivetti, Commodore, AST.

MP type	80C88
Clock frequency, MHz	4,77
RAM capacity, KB	256...640
Diameter of NGMD, mm	89
Capacity of float drive, Kbyte	720
Display diameter, mm	254
Display type	LCD-c
Resolution, dots	640x200
Screen capacity, characters	25x80
Total number of keys	78
Number of function keys	10
Types of PU interfaces	Centronics
operating system	PC DOS 3.2
Weight, kg	14,5
Note. LCD - liquid crystal contrast.