Nem szokasom szivesseget kerni - foleg nem olyan emberektol akiket nemigazan ismerek - de most egy kicsit szorult helyzetbe vagyok.
Holnapra le kellene forditanom a lenti szoveget. De egyreszt se idom, se megfelelo angoltudasom sincs ehhez a szoveghez. Tehat
ha valakinek nagyon sok szabadideje van, ill. lenne olyan rendes, hogy besegitene nekem, azt megkoszonnem. (Cserebe rakok fel kepet, akirol ker!!! )
En mar annak is orulnek, ha egy bekezdest lefordit valaki, mert tudom, hogy sok ez a szoveg. Leforditanam en magamnak szivesen csakhat nekem nem az angol volt a fonyelvem meg anno az iskolaban.
Idézet
Computing
6.1. Architecture of a Computer
CPU
The main part of the computer system is the so-called Central Processing Unit (CPU). It controls the computer system and executes the instructions of the computer programme. Its main parts are the computational unit, data registers, and control and riming units. Nowadays it is usually implemented in a single chip, so called microprocessor. The microprocessor is generally designed for a broad range of applications. There are also microprocessors dedicated for a given task. There are several internal storage locations (registers) in the processor. The most important of those is called an accumulator. The majority of instructions deal with transferring data between memory and the accumulator(s). Instructions are executed according to the/efc/z, decode and execute cycle. Data is manipulated in the accumulator. The processor consists of a large bank of general registers. All the registers are the same size, and several instructions deal with the manipulation of registers.
6.2. System Bus
Exchanging data between the CPU and the memory or I/O devices requires a common
set of bus lines that can transfer data in either direction. The bidirectional bus uses time
divisions to transfer data from the CPU to the memory or I/O during one transfer time and to transfer data from the memory or I/O the CPU during a different time. The bus that can transfer data in two directions is called a bidirectional bus.
The CPU addresses the memory with the unidirectional Address bus. The addressable memory size depends on the number of lines.
Data bus is an integration of data line (8-bit, 16-bit, 32-bit or 64-bit) placed between a CPU and its peripheral devices, and memory devices that can transfer data to read and write. Data bus is a bidirectional bus.
The Control bus means a collection of bus lines for receiving and passing on the request/ acknowledge signals, timing signals, status display signals etc. when data is transferred back and forth between the CPU, memory and I/O devices. The address bus, data bus and control bus from the main CPU is collectively referred to as the System bus.
6.3. Buses in Computers
This section specifically deals with the bus systems used in IBM-PC and compatibles.
Abus system is a highway that interconnects two or more devices. The highway consists
of a number of wires that perform the following functions:
• data transfer,
• timing and synchronisation of data,
• bus arbitration.
In a designated transfer, one device is the master, and the other device(s) is (are) the slave(s). The master device controls the transfer of data and issues commands to accomplish this.
The PC bus is an input/output bus that facilitates the transfer of data between the CPU and peripherals. There are several types of PC buses, for example ISA (Industry Standard Architecture), EISA (Extended Industrial Standard), VESA (Video Electronics Standard), PCI (Personal Component Interconnect), SCSI (Small Computer System Interface) and PCMCIA (Personal Computer Memory Card International Association).
Originally developed for the IBM-PC computer (8086,8 bit bus) the ISA bus was extended in 1984 to support 16 bits when the 80286 AT computer was introduced. Its main features are: single bus master; support for up to 16 MB of memory; 8/16 bit data width; widely accepted and many cards available; 8 MHz clock rate for data transfers. A bus controller chip provides the interface between the processor, memory sub-system and the peripheraldevices. Whilst the processor can talk to the memory sub-system at 33 MHz, it is forced to talk to the peripheral devices at 8 MHz due to the ISA bus controller chip.
6.4. Memory
The Read Only Memory (ROM) is a form of memory in which the information is
permanently stored in the 1C and cannot be changed.
The computer memory (RAM) contains the current program and data information. The Random Access Memory (RAM) is a volatile semiconductor memory chip in which the information may be randomly written, or read from any address location. The Dynamic Random Access Memory (DRAM) is a type of RAM that must be periodically refreshed to maintain the state of the stored data (see Figure 6.1.). The Video RAM (VRAM) is a two-port DRAM tailored to the needs of graphics controllers.
6.5. Interfaces
An interface is the part of a computer that establishes a connection between two or
more devices, with determined
• electrical voltages used,
• pin assignments and
• sequence of signals used to initiate and control the transfer of data.
Interfaces consist of one or more wires, and support two or more devices. In addition
an interface can support several masters and several listeners. The type of interface used depend upon the data requirements.
The IDE (Integrated Drive Electronics) interface was developed by Western Digital and Compaq Corporation in the late 1980's. It is also known as the ATA interface (advanced types: ATA66 and ATA100).
The ATAPI (ATA Packet Interface) standard was designed to support CD-ROM using IDE. It is inexpensive and works on the existing IDE adapter.
SCSI (Small Computer Systems Interface) bus system is a standard for connecting peripheral devices to a computer system. Most manufacturers and computer systems support it.
6.6. Peripherals
Hard disks work on magnetic principles. In computers, data is represented in binary
format. Binary data has two states,'!' or '0'. Magnetism also has two states, 'north' and
'south'', so magnetism is a good way of storing data. The surface of the hard disk is
coated with very fine ferrous oxide particles, each of which act and behave like little
magnets.
In a hard disk drive, the mechanism that performs the function of converting digital O's and 1's into magnetic states, which can magnetise the surface areas of the disk, is called the write head. A similar head, called the read head, is used to detect the magnetic states on the surface of the disk and convert them back into digital states.
In practice the read and write heads are combined into a single read/write head that performs both functions.
CD-ROM is the abbreviation of Compact Disc Read Only Memory. These optical disks use laser technology to implement data storage. They are similar to audio compact disks (CDs). Optical disks for PC's can store about 700 MB of data. The early, so-called double speed CD drives used to have an access time of about 300 ms (little slower than floppy). The disk is 12 cm in diameter and made from plastic material with a coating on one side which holds the stored data.
The laser beam is shone onto the surface of the disk. Data is stored as a sequence of surface variations called lands (flat surface) and pits (bumps or holes), which represent binary O's and 1's. The laser beam is moved to follow the spiral track of the data stored on the disk; it detects the pits and lands as it follows the spiral track. A light sensitive diode picks up the reflected laser light from the surface of the disk, and converts the light to digital data.
CD-Writeable (CD-R) is a writeable CD-ROM. A special recorder drive is used that writes the image to the CD-R. Normal CD's cannot be used to write, rather, special CD-R disks are used. The user creates an image of the CD on the hard disk of the computer that is then burnt onto the blank CD. Data recorded onto a CD-R cannot be overwritten.
The storage capacity of a CD-R is the same as that of a CD-ROM, limited to 650 MB of net data or 74 minutes of audio.CD-ReWriteable (CD-RW) is a CD-R that can be rewritten, hence it is known as CD-RW. The storage capacity of a CD-RW is the same as that of a CD-ROM.
Digital Video Disk (DVD) is a new standard which offers higher data storage and faster data transfer than existing CD-ROMs. A standard DVD holds 4.7 GB per layer, dual layer single sided DVD holds 8.5 GB on a single side.
6.7. Keyboards
The keyboard is the most widely used means of entering information into a computer. Pressing a key on the keyboard generates a code that represents the character associated with the key. The keypress is converted to ASCII format, then processed by the computer.
Scanners
Scanners are devices that scan documents containing text or graphics and convert them into a bitmap (picture image). The image may be in black and white, grey scale or colour depending upon the features of the scanner.
The resolution of a scanner refers to how many pixels (dots) per inch it can detect and reproduce in the final bitmap image.
Scanners are also used with OCR (Optical Character Recognition) to scan text documents as graphic images, then convert them back to text again, saving the user having to retype the entire document.
Dot matrix printers are suitable for draft copies and home use, where quality is not critical. Dot printers impact printing using an inked ribbon. Characters are formed from a matrix of dots.
Laser-jet printers are very common today. First laser-jet printers ran at 4 pages per minute (ppm), with a resolution of 300 dots per inch (dpi). Both the speed of printing and resolution have increased. These type of printers have the best image of all.
Because of their good quality at an affordable price, ink-jet printers have become the most popular printers for home computers and low cost printing. In ink-jet printers conductive ink is forced through a small nozzle producing a small droplet of ink, which is propelled towards the surface of the medium. High print quality, but low speed is typical. Using special material overhead transparencies also can be printed.
6.8. Monitors are devices used to display information from the computer. The monitor screens used in computer systems are of a much higher quality than television set monitors.
Monitors come in various sizes, commonly starting at 14", then 15", as well as 17" or even 21". This is the size of the tube measured across the diagonal from corner to corner. The viewable part is a bit smaller, except for LCD screens. Larger sizes are required for higher resolutions, but the larger the size, the more expensive the monitor is.
6.9. General Purpose Microcomputers, PCs, Clones
Personal computers are used for different purposes. Originally the International Business Machine (IBM)™ Personal Computers (PC) were manufactured and sold all over the world. Later on several equipment manufacturers produced similar microcomputers (clones).
Generally, the word 'compatible' indicates the compatibility of the electrical characteristics, pin connections and packages. It can also refer to a microprocessor's ability to execute the same functions or to run the same instruction set. Many microcomputer families were developed with upward compatibility (for example . i80286®, i80386®, 180486®).
6.10. Motherboard and Slots
The motherboard of a small- to medium-sized computer system is the main printed circuit board (PCB) on which the CPU and associated circuits are mounted. In PCs, memory and many I/O devices are also on the motherboard. Other, often optional, I/O and memory components are mounted on small daughter boards and inserted vertically into sockets (slots) on the motherboard. On a motherboard, for example, there are 62-pin (A1...A31 and B1...B31) and 18-pin (Side A and Side B ) I/O, and 62-pin memory (A1...A31 and B1...B31) slots.
Most PCs are built around chip sets, A chip set is a collection of ICs that generally mates a CPU with DRAMs, SRAMs (if a secondary cache is included), and the usual assortment of I/O devices.
6.11. Software
Introduction
Software is called 'resident', when it is always residing in memory while the computer is operating. For example, a portion of the operating system or a frequently used service program may be resident software.
System Programs
The Structure of MS-DOS
MS-DOS is partitioned into several layers (BIOS, kernel and command processor). The hardware on which the application program is running, is separated from (and connected to) it by the operating system.
The manufacturer of the system provides the computer system specific 'BIOS' (Basic Input/Output System). It contains the default resident hardware-dependent drivers for the following devices: display and keyboard (CON), printer (PRN), date and time (CLOCKS) etc. In IBM PC and clones the most primitive parts of the hardware drivers are located in read-only memory (ROM). These are also used in diagnostics, and by the system start-up program.
The 'command processor', or shell, is the user's interface to the operating system.
Graphic Operational Systems, Windows-systems
To solve some of the problems with DOS - command line interface, lack of graphics -, Graphic operational systems were created. DOS was only able to run one program (single task) at a time. The best known graphic operational system, Windows is a true 'multitasking' operating system. With Windows, at least the frames of all the programs look alike. The screen in general looks the same no matter what program is running, and the controls for the programs are consistent.
6.12. Applications
Application program is a computer program that is used to perform a specific task or to be used in a general application such as word processing.
Word Processors
The term 'word processing' refers to application programs that are used to compose text for various purposes.
Databases
A database uses the concept that information will always follow a given format. This format breaks down the individual pieces of information into blocks calledfields. Each group of fields is called a record; for instance in the case of a mailing list. Name, Street, City, Zip, Phone constitute a record.
Spreadsheet Programs
Complicated calculations in tabular form can be done very easily using spreadsheet programs. Firstly these were only used in bookkeeping; today these are fundamental parts of integrated office program packages.
Graphics
Graphics programs are used for example for technical design. These are not character based but instead 'pixel' based programs. 'Pixel' is derived from Picture Element. Each addressable or definable spot on a video or graphics image is called a pixel. The size of screens and images is defined in terms of pixels. Pixels have depth, measured in bits. The more bits per pixel, the more different shades of grey or different colours each pixel can have.
6.13. Languages
Assembly Language
The language closest to the PC hardware is 'machine language', in binary code, which is only readable for the computer itself. The 'assembly language' is a symbolic computer programming language, which is a direct representation of the binary code that is used to instruct or program a microprocessor.
An assembly language programmer has to work and think on the machine language level. The written assembly language program will be converted into the actual machine code by an assembler program. Programming in assembly language is a very time consuming activity and is only worth using when crucial problems make it necessary (low level control, real-time applications).
High Level Languages
Rather than machine language, which executes only one instruction per statement, a high level language is capable of expressing several instructions with a single word, simplifying the structure of a software program. For example, C, C++, Pascal are all high level languages.
The C Programming Language
C is a general-purpose high level programming language specifically created in order to allow the programmer access to almost all of the machine's internal registers, I/O slots and absolute addresses. This language features transportability among different machines, so is it called a portable language.
6.1. Architecture of a Computer
CPU
The main part of the computer system is the so-called Central Processing Unit (CPU). It controls the computer system and executes the instructions of the computer programme. Its main parts are the computational unit, data registers, and control and riming units. Nowadays it is usually implemented in a single chip, so called microprocessor. The microprocessor is generally designed for a broad range of applications. There are also microprocessors dedicated for a given task. There are several internal storage locations (registers) in the processor. The most important of those is called an accumulator. The majority of instructions deal with transferring data between memory and the accumulator(s). Instructions are executed according to the/efc/z, decode and execute cycle. Data is manipulated in the accumulator. The processor consists of a large bank of general registers. All the registers are the same size, and several instructions deal with the manipulation of registers.
6.2. System Bus
Exchanging data between the CPU and the memory or I/O devices requires a common
set of bus lines that can transfer data in either direction. The bidirectional bus uses time
divisions to transfer data from the CPU to the memory or I/O during one transfer time and to transfer data from the memory or I/O the CPU during a different time. The bus that can transfer data in two directions is called a bidirectional bus.
The CPU addresses the memory with the unidirectional Address bus. The addressable memory size depends on the number of lines.
Data bus is an integration of data line (8-bit, 16-bit, 32-bit or 64-bit) placed between a CPU and its peripheral devices, and memory devices that can transfer data to read and write. Data bus is a bidirectional bus.
The Control bus means a collection of bus lines for receiving and passing on the request/ acknowledge signals, timing signals, status display signals etc. when data is transferred back and forth between the CPU, memory and I/O devices. The address bus, data bus and control bus from the main CPU is collectively referred to as the System bus.
6.3. Buses in Computers
This section specifically deals with the bus systems used in IBM-PC and compatibles.
Abus system is a highway that interconnects two or more devices. The highway consists
of a number of wires that perform the following functions:
• data transfer,
• timing and synchronisation of data,
• bus arbitration.
In a designated transfer, one device is the master, and the other device(s) is (are) the slave(s). The master device controls the transfer of data and issues commands to accomplish this.
The PC bus is an input/output bus that facilitates the transfer of data between the CPU and peripherals. There are several types of PC buses, for example ISA (Industry Standard Architecture), EISA (Extended Industrial Standard), VESA (Video Electronics Standard), PCI (Personal Component Interconnect), SCSI (Small Computer System Interface) and PCMCIA (Personal Computer Memory Card International Association).
Originally developed for the IBM-PC computer (8086,8 bit bus) the ISA bus was extended in 1984 to support 16 bits when the 80286 AT computer was introduced. Its main features are: single bus master; support for up to 16 MB of memory; 8/16 bit data width; widely accepted and many cards available; 8 MHz clock rate for data transfers. A bus controller chip provides the interface between the processor, memory sub-system and the peripheraldevices. Whilst the processor can talk to the memory sub-system at 33 MHz, it is forced to talk to the peripheral devices at 8 MHz due to the ISA bus controller chip.
6.4. Memory
The Read Only Memory (ROM) is a form of memory in which the information is
permanently stored in the 1C and cannot be changed.
The computer memory (RAM) contains the current program and data information. The Random Access Memory (RAM) is a volatile semiconductor memory chip in which the information may be randomly written, or read from any address location. The Dynamic Random Access Memory (DRAM) is a type of RAM that must be periodically refreshed to maintain the state of the stored data (see Figure 6.1.). The Video RAM (VRAM) is a two-port DRAM tailored to the needs of graphics controllers.
6.5. Interfaces
An interface is the part of a computer that establishes a connection between two or
more devices, with determined
• electrical voltages used,
• pin assignments and
• sequence of signals used to initiate and control the transfer of data.
Interfaces consist of one or more wires, and support two or more devices. In addition
an interface can support several masters and several listeners. The type of interface used depend upon the data requirements.
The IDE (Integrated Drive Electronics) interface was developed by Western Digital and Compaq Corporation in the late 1980's. It is also known as the ATA interface (advanced types: ATA66 and ATA100).
The ATAPI (ATA Packet Interface) standard was designed to support CD-ROM using IDE. It is inexpensive and works on the existing IDE adapter.
SCSI (Small Computer Systems Interface) bus system is a standard for connecting peripheral devices to a computer system. Most manufacturers and computer systems support it.
6.6. Peripherals
Hard disks work on magnetic principles. In computers, data is represented in binary
format. Binary data has two states,'!' or '0'. Magnetism also has two states, 'north' and
'south'', so magnetism is a good way of storing data. The surface of the hard disk is
coated with very fine ferrous oxide particles, each of which act and behave like little
magnets.
In a hard disk drive, the mechanism that performs the function of converting digital O's and 1's into magnetic states, which can magnetise the surface areas of the disk, is called the write head. A similar head, called the read head, is used to detect the magnetic states on the surface of the disk and convert them back into digital states.
In practice the read and write heads are combined into a single read/write head that performs both functions.
CD-ROM is the abbreviation of Compact Disc Read Only Memory. These optical disks use laser technology to implement data storage. They are similar to audio compact disks (CDs). Optical disks for PC's can store about 700 MB of data. The early, so-called double speed CD drives used to have an access time of about 300 ms (little slower than floppy). The disk is 12 cm in diameter and made from plastic material with a coating on one side which holds the stored data.
The laser beam is shone onto the surface of the disk. Data is stored as a sequence of surface variations called lands (flat surface) and pits (bumps or holes), which represent binary O's and 1's. The laser beam is moved to follow the spiral track of the data stored on the disk; it detects the pits and lands as it follows the spiral track. A light sensitive diode picks up the reflected laser light from the surface of the disk, and converts the light to digital data.
CD-Writeable (CD-R) is a writeable CD-ROM. A special recorder drive is used that writes the image to the CD-R. Normal CD's cannot be used to write, rather, special CD-R disks are used. The user creates an image of the CD on the hard disk of the computer that is then burnt onto the blank CD. Data recorded onto a CD-R cannot be overwritten.
The storage capacity of a CD-R is the same as that of a CD-ROM, limited to 650 MB of net data or 74 minutes of audio.CD-ReWriteable (CD-RW) is a CD-R that can be rewritten, hence it is known as CD-RW. The storage capacity of a CD-RW is the same as that of a CD-ROM.
Digital Video Disk (DVD) is a new standard which offers higher data storage and faster data transfer than existing CD-ROMs. A standard DVD holds 4.7 GB per layer, dual layer single sided DVD holds 8.5 GB on a single side.
6.7. Keyboards
The keyboard is the most widely used means of entering information into a computer. Pressing a key on the keyboard generates a code that represents the character associated with the key. The keypress is converted to ASCII format, then processed by the computer.
Scanners
Scanners are devices that scan documents containing text or graphics and convert them into a bitmap (picture image). The image may be in black and white, grey scale or colour depending upon the features of the scanner.
The resolution of a scanner refers to how many pixels (dots) per inch it can detect and reproduce in the final bitmap image.
Scanners are also used with OCR (Optical Character Recognition) to scan text documents as graphic images, then convert them back to text again, saving the user having to retype the entire document.
Dot matrix printers are suitable for draft copies and home use, where quality is not critical. Dot printers impact printing using an inked ribbon. Characters are formed from a matrix of dots.
Laser-jet printers are very common today. First laser-jet printers ran at 4 pages per minute (ppm), with a resolution of 300 dots per inch (dpi). Both the speed of printing and resolution have increased. These type of printers have the best image of all.
Because of their good quality at an affordable price, ink-jet printers have become the most popular printers for home computers and low cost printing. In ink-jet printers conductive ink is forced through a small nozzle producing a small droplet of ink, which is propelled towards the surface of the medium. High print quality, but low speed is typical. Using special material overhead transparencies also can be printed.
6.8. Monitors are devices used to display information from the computer. The monitor screens used in computer systems are of a much higher quality than television set monitors.
Monitors come in various sizes, commonly starting at 14", then 15", as well as 17" or even 21". This is the size of the tube measured across the diagonal from corner to corner. The viewable part is a bit smaller, except for LCD screens. Larger sizes are required for higher resolutions, but the larger the size, the more expensive the monitor is.
6.9. General Purpose Microcomputers, PCs, Clones
Personal computers are used for different purposes. Originally the International Business Machine (IBM)™ Personal Computers (PC) were manufactured and sold all over the world. Later on several equipment manufacturers produced similar microcomputers (clones).
Generally, the word 'compatible' indicates the compatibility of the electrical characteristics, pin connections and packages. It can also refer to a microprocessor's ability to execute the same functions or to run the same instruction set. Many microcomputer families were developed with upward compatibility (for example . i80286®, i80386®, 180486®).
6.10. Motherboard and Slots
The motherboard of a small- to medium-sized computer system is the main printed circuit board (PCB) on which the CPU and associated circuits are mounted. In PCs, memory and many I/O devices are also on the motherboard. Other, often optional, I/O and memory components are mounted on small daughter boards and inserted vertically into sockets (slots) on the motherboard. On a motherboard, for example, there are 62-pin (A1...A31 and B1...B31) and 18-pin (Side A and Side B ) I/O, and 62-pin memory (A1...A31 and B1...B31) slots.
Most PCs are built around chip sets, A chip set is a collection of ICs that generally mates a CPU with DRAMs, SRAMs (if a secondary cache is included), and the usual assortment of I/O devices.
6.11. Software
Introduction
Software is called 'resident', when it is always residing in memory while the computer is operating. For example, a portion of the operating system or a frequently used service program may be resident software.
System Programs
The Structure of MS-DOS
MS-DOS is partitioned into several layers (BIOS, kernel and command processor). The hardware on which the application program is running, is separated from (and connected to) it by the operating system.
The manufacturer of the system provides the computer system specific 'BIOS' (Basic Input/Output System). It contains the default resident hardware-dependent drivers for the following devices: display and keyboard (CON), printer (PRN), date and time (CLOCKS) etc. In IBM PC and clones the most primitive parts of the hardware drivers are located in read-only memory (ROM). These are also used in diagnostics, and by the system start-up program.
The 'command processor', or shell, is the user's interface to the operating system.
Graphic Operational Systems, Windows-systems
To solve some of the problems with DOS - command line interface, lack of graphics -, Graphic operational systems were created. DOS was only able to run one program (single task) at a time. The best known graphic operational system, Windows is a true 'multitasking' operating system. With Windows, at least the frames of all the programs look alike. The screen in general looks the same no matter what program is running, and the controls for the programs are consistent.
6.12. Applications
Application program is a computer program that is used to perform a specific task or to be used in a general application such as word processing.
Word Processors
The term 'word processing' refers to application programs that are used to compose text for various purposes.
Databases
A database uses the concept that information will always follow a given format. This format breaks down the individual pieces of information into blocks calledfields. Each group of fields is called a record; for instance in the case of a mailing list. Name, Street, City, Zip, Phone constitute a record.
Spreadsheet Programs
Complicated calculations in tabular form can be done very easily using spreadsheet programs. Firstly these were only used in bookkeeping; today these are fundamental parts of integrated office program packages.
Graphics
Graphics programs are used for example for technical design. These are not character based but instead 'pixel' based programs. 'Pixel' is derived from Picture Element. Each addressable or definable spot on a video or graphics image is called a pixel. The size of screens and images is defined in terms of pixels. Pixels have depth, measured in bits. The more bits per pixel, the more different shades of grey or different colours each pixel can have.
6.13. Languages
Assembly Language
The language closest to the PC hardware is 'machine language', in binary code, which is only readable for the computer itself. The 'assembly language' is a symbolic computer programming language, which is a direct representation of the binary code that is used to instruct or program a microprocessor.
An assembly language programmer has to work and think on the machine language level. The written assembly language program will be converted into the actual machine code by an assembler program. Programming in assembly language is a very time consuming activity and is only worth using when crucial problems make it necessary (low level control, real-time applications).
High Level Languages
Rather than machine language, which executes only one instruction per statement, a high level language is capable of expressing several instructions with a single word, simplifying the structure of a software program. For example, C, C++, Pascal are all high level languages.
The C Programming Language
C is a general-purpose high level programming language specifically created in order to allow the programmer access to almost all of the machine's internal registers, I/O slots and absolute addresses. This language features transportability among different machines, so is it called a portable language.