Translate the following texts

1. BIOS (Basic Input-Output System)

With any computer system a fundamental design problem is how to provide for the basic communication between the processor and the devices used to obtain or display data, such as the video screen, keyboard, and parallel and serial ports.

In personal computers, the BIOS (Basic Input-Output System) solves this problem by providing a set of routines for direct control of key system hardware such as disk drives, the keyboard, video interface, and serial and parallel ports. Once DOS is running, routines in the operating system kernel can access the hardware by making calls to the BIOS routines. In turn, application programs can call the operating system, which passes requests on to the BIOS routines.

In modern PCs the BIOS setup screen also allows users to specify the order of devices to be used for loading system start-up code. This, for example, might allow a potentially corrupted hard drive to be bypassed in favor of a bootable CD or DVD with disk repair tools. Another scenario would allow users to boot from a USB memory stick and use a preferred operating system and working files without disturbing the PC’s main setup. The data on these chips is maintained by a small on- board battery so settings are not lost when the main system power is turned off.

Additionally, modern PC BIOS chips use “flash memory to store the code”. These chips can be “flashed” or reprogrammed with newer versions of the BIOS, enabling the support of newer devices without having to replace any chips.

Binding

Designers of program compilers are faced with the question of when to translate a statement written in the source language into final instructions in machine language. This can happen at different times depending on the nature of the statement and the decision of the compiler designer.

Many programming languages use formal data types (such as integer, floating point, double, string, and so on) that result in allocation of an exact amount of storage space to hold the data. A statement that declares a variable with such a type can be effectively bound immediately (that is, a final machine code statement can be generated). This is also called compile-time binding.

However, there are a variety of statements for which binding must be deferred until more information becomes available. For example, it is common for programmers to use libraries of precompiled routines. A statement that calls such a routine cannot be turned immediately into machine language because the compiler doesn’t know the actual address where the routine will be embedded in the final compiled program. (That address will be determined by a program called a linker that links the object code from the source program to the library routines called upon by that code).

Another aspect of binding arises when there is more than one object in a program with the same name. In languages such as C or Pascal that use a nested block structure, lexical binding can determine that a name refers to the closest declaration of that name—that is, the smallest scope that contains that name. In a few languages such as Lisp, however, the reference for a name depends how (or for what) the function is being called, so binding can be done only at run time.

Chipset

In personal computers a chipset is a group of integrated circuits that together perform a particular function. System purchasers generally think in terms of the processor itself (such as a Pentium III, Pentium IV, or competitive chips from AmD or Cyrix). However they are really buying a system chipset that includes the microprocessor itself and often a memory cache as well as the chips that control the memory bus. The overall performance of the system depends not just on the processor’s architecture (including data width, instruction set, and use of instruction pipelines) but also on the type and size of the cache memory, the memory bus and the speed with which the processor can move data to and from memory.

In addition to the system chipset, other chipsets on the motherboard are used to support functions such as graphics (the AgP, or Advanced graphics Port, for example), drive connection (EIDE controller), communication with interconnections to expansion cards. At the end of the 1990s, the PC marketplace had chipsets based on two competing architectures. Intel, which originally developed an architecture called Socket 7, has switched to the more complex Slot-1 architecture, which is most effective for multiprocessor operation but offers the advantage of including a separate bus for accessing the cache memory. Meanwhile, Intel’s main competitor, AmD, has enhanced the Socket 7 into “Super Socket 7” and is offering faster bus speeds. On the horizon may be completely new architecture. In choosing a system, consumers are locked into their choice because the microprocessor pin sockets used for each chipset architecture are different.

4. Have you noticed how much your computer screen flickers? This may be because your computer monitor uses CRT technology. This kind of technology offers colour and high-resolution pictures for relatively little money but the monitors are large, use a lot of energy, can flicker and emit electromagnetic radiation.

In recent years flat screens have become increasingly popular. Users talk of benefits such as more desk space, how easy they are to adjust for tilt and height, crisper, clearer images and the total elimination of screen flicker. Most flat screens are based on LCD technology which has a lot of benefits over CRT technology. But there is one major drawback to flat screens: their cost.

The Types of Memory

In all types of computer systems, from a small dedicated microprocessor system to the largest full size computer, memory plays a very essential part. The memory section of the microcomputer system serves the purpose of holding either information, that the computer will need, or information, that the computer has already generated, which will be utilized in the future. In other words, the memory of a microcomputer is used for storing the program and the data. There are two basic types of memory, namely read/write memory whose contents can be altered by writing new information into it and read-only memory (ROM) whose contents are fixed. Read/write memory is usually exclusively referred to as random-access memory (RAM) for historical reasons, although strictly speaking most modern read-only memories can also be accessed in a random order and therefore qualify for such a description. Random means that any one of the different memory locations can be written into or read from with equal ease and that it takes the same amount of time to address any one of the different memory locations within the same device.

The semiconductor RAM memory is of the volatile type. That is, when power is removed, all information previously written in memory is lost.

A problem develops because memory needs to have both non-volatility and read/write capability. At the time of this writing, there is not one RAM chip that has both of these desirable functions. The memory chips are either of the RAM family and have the read/write capability but are volatile or of the ROM family and have only the read capability but are non-volatile. So the read/write feature of the RAM makes it a very versatile memory device. However, its volatility presents a special problem.

Recently, technology has advanced to the stage where nonvolatile RAM's can be made. These do not lose their information when the power in them is interrupted.

The next generation of semiconductor RAM memories has advanced to higher density (more memory cells/chip) and higher operating frequencies.

The essential difference as far as the user is concerned is hat ROM retains the information in it even without power, even if a program error or other fault causes the system to try and overwrite the contents of the ROM. It is therefore used mainly for storing fixed programs and constants.

As the term ROM implies, this type of memory can only be read from and not written into by the user.

Since the ROM has the feature of nonvolatility, it lends it self to applications such as dedicated subroutines including mathematical packages, monitor programs, debug programs and any program that has a fixed structure where there is no need to make changes to the program that resides in the ROM.

Дата добавления: 2015-11-14