求英語翻譯 不要機(jī)器翻譯的
1.Programming in machine languages means speaking directly to the computer in the language of 1s and 0s it understands. Machine language is the fastest because no translation is required on the computer’s part. However, it is almost impossible to learn-imagine having to enter a string（字符串） of hundreds of binary digits just to tell the computer to perform a basic operation like adding numbers. Nevertheless, this is how the first generation（代） computers were programmed.
2. Operating systems have developed over the past thirty years for two main purposes. First, they provide a convenient environment for the development and execution of programs. Second, operating systems attempt to schedule computational activities to ensure good performance of the computing system. The operating system must ensure correct operation of the computer system. To prevent user programs from interfering with the proper operation of the system, the hardware was modified to create two modes: user mode and monitor mode.
3. The input/output and secondary（輔助） storage units are sometimes called peripheral devices (or just peripherals). This terminology refers to the fact that although these devices are not a part of the CPU, they are often located near it. Besides, a computer system also includes buses, ROM (read only memory), RAM (random access memory), parallel（并行） port and serial（串行） port, hard disk, floppies and CD (computer disk) drive, and so on.
4.Output DevicesLike input units, output devices are instruments of interpretation and communication between humans and computer systems of all sizes. These devices take output results from the CPU in machine-coded form and convert them into a form that can be used (a) by people (e.g., a printed and/or displayed report) or (b) as machine input in another processing cycle.
5. The operating system must ensure correct operation of the computer system. To prevent user programs from interfering with the proper operation of the system, the hardware was modified to create two modes: user mode and monitor mode. Various instructions (such as I/O instructions and halt instructions) are privileged and can only be executed in monitor mode. The memory in which the monitor resides must also be protected from modification by the user. A timer prevents infinite loops. Once these changes (dual mode, privileged instructions, memory protection, timer interrupt) have been made to the basic computer architecture, it is possible to write a correct operating system.
6. In personal computer systems, display screen and desktop printers are popular output devices. Larger and faster printers, many online workstations, and magnetic tape drives are commonly found in larger systems.