计算机操作系统 内存

什么是记忆？ (What is Memory?)

The essential component of the computer is its Memory. It is assembled on the motherboard as it is a storage device used for storing data and instructions for performing a task on the system.

计算机的基本组成部分是其内存。 它被组装在主板上，因为它是用于存储数据和在系统上执行任务的指令的存储设备。

• A memory is used to store data and instructions. It is the storage space in a computer, where data is to be processed and all the instructions are stored that are required for processing. In simple words, it works just like a human brain where we can store memories.

  存储器用于存储数据和指令。 它是计算机中的存储空间，将在其中处理数据并存储处理所需的所有指令。 简而言之，它就像人类的大脑可以存储记忆一样。

• Storage devices are hardware devices that are capable of storing and fetching data. Hard drives or optical discs are an example of such storage devices.

  存储设备是能够存储和获取数据的硬件设备。 硬盘驱动器或光盘是此类存储设备的示例。

• Without memory, the computer can't perform a single task.

  没有内存，计算机将无法执行单个任务。

电脑内存类型 (Types of computer memory)

There are two types of memories:

有两种类型的记忆：

1. Primary memory

   主存

2. Secondary memory

   二级记忆

Types of Computer Memory

电脑内存类型

1)主存(主存) (1) Primary Memory (Main Memory))

It is also referred to as Main Memory. It is volatile. The reason behind is, Primary memory holds only those data and instructions on which the computer is currently working that is it does not store the data permanently.

它也称为主存储器。 它是易挥发的。 其背后的原因是，主内存仅保存计算机当前正在处理的那些数据和指令，因为它不会永久存储数据。

• It also stores the operating system and data required to run the computer.

  它还存储操作系统和运行计算机所需的数据。

• It is a limited capacity memory and data or information is lost when power is switched off. Primary Memory is generally constructed with a semiconductor device.

  它是容量有限的存储器，并且在关闭电源时会丢失数据或信息。 主存储器通常由半导体器件构成。

• Registers are much faster than these memories but it is faster than secondary memory.

  寄存器比这些存储器快得多，但比辅助存储器快。

• It contains all the data and instructions that are required to be processed.

  它包含所有需要处理的数据和指令。

It is further divided into two subcategories RAM and ROM.

它进一步分为RAM和ROM两个子类别。

i) RAM (Random Access Memory)

i)RAM(随机存取存储器)

It is Random Access Memory because of the random selection of memory locations. It performs both read and writes operations on memory. It stores data temporarily.

由于是随机选择存储位置，因此它是随机访问存储器。 它在内存上执行读取和写入操作。 它临时存储数据。

If power failures happen in the system during memory access then you will lose your data permanently. So, RAM is a volatile memory.

如果在访问内存期间系统发生电源故障，那么您将永久丢失数据。 因此，RAM是易失性存储器。

RAM categorized into following types:

RAM分为以下几种类型：

1. DRAM

   记忆体

2. SRAM

   SRAM

a) SRAM (Static random access memory)

a)SRAM(静态随机存取存储器)

It holds data in a static form, that is, as long as the memory has the power as the dynamic RAM, it is not needed to refresh it again and again.

它以静态形式保存数据，也就是说，只要内存具有动态RAM的功能，就不需要一次又一次刷新它。

• Static RAM provides faster access to data and is more expensive than DRAM as each cell must contain multiple transistors.

  静态RAM提供更快的数据访问速度，并且比DRAM昂贵，因为每个单元必须包含多个晶体管。

• SRAM does not use capacitors.

  SRAM不使用电容器。

• SRAM is also highly recommended for use in PCs, peripheral equipment, printers, LCD screens, hard disk buffers, router buffers and buffers in CDROM / CDRW drives.

  强烈建议将SRAM用于PC，外围设备，打印机，LCD屏幕，硬盘缓冲区，路由器缓冲区以及CDROM / CDRW驱动器中的缓冲区。

b) Dynamic RAM (Dynamic random access memory)

b)动态RAM(动态随机存取存储器)

It is a type of random-access memory used in computing devices. It is made up of capacitors and transistors.

它是计算设备中使用的一种随机存取存储器。 它由电容器和晶体管组成。

• This type of memory uses separate capacitors or transistors to stores each bit of data and it has two states of value in one bit called 0 and 1.

  这种类型的存储器使用单独的电容器或晶体管来存储数据的每一位，并且它在一个位(称为0和1)中具有两种有价状态。

• As compared with other RAM's it is less expensive.

  与其他RAM相比，它更便宜。

• Data were written by DRAM at the byte-level.

  数据是在字节级别由DRAM写入的。

• In DRAM, data is written at the byte-level and it reads data at the multiple-byte page level.

  在DRAM中，数据以字节级别写入，并以多字节页面级别读取数据。

• DRAM requires less power than other RAMs.

  DRAM比其他RAM耗电少。

ii) ROM (Read Only Memory)

ii)ROM(只读存储器)

ROM offers huge types of standards to save data as it is a permanent memory location. But it works with the read-only operation. whenever power failure occurs during the ROM memory work in computers then no data lose happens.

ROM提供了多种类型的标准来保存数据，因为它是永久性的存储位置。 但是它可以与只读操作一起使用。 只要计算机中的ROM存储器工作期间发生电源故障，就不会发生数据丢失。

• It is Used where the programming requires no change and also in embedded systems or.

  它用于不需要更改编程的地方，也可以在嵌入式系统中使用。

• It is Used in peripheral devices and calculators.

  它用于外围设备和计算器。

Types of Read Only Memory (ROM)

只读存储器(ROM)的类型

1. PROM (Programmable read-only memory)

   PROM(可编程只读存储器)

2. EPROM (Erasable Programmable read only memory)

   EPROM(可擦可编程只读存储器)

3. EEPROM (Electrically erasable programmable read only memory)

   EEPROM(电可擦可编程只读存储器)

a) PROM (Programmable read-only memory)

a)PROM(可编程只读存储器)

Developers created a type of ROM known as programmable read-only memory (PROM) because Creating ROM chips from scratch are time-consuming and very expensive.

开发人员创建了一种称为可编程只读存储器(PROM)的ROM，因为从头开始创建ROM芯片既耗时又非常昂贵。

• It can be coded by the user. Once coded, the data and instructions in it cannot be changed.

  可以由用户编码。 一旦编码，其中的数据和指令将无法更改。

• It is used to store permanent data in digital electronic devices.

  它用于在数字电子设备中存储永久数据。

• It can be bought at a low cost as compared to other RAMs.

  与其他RAM相比，它可以低成本购买。

b) EPROM (Erasable Programmable read only memory)

b)EPROM(可擦可编程只读存储器)

This is the type of memory that can be reprogrammed. We can erase data from it and reprogram it that is erase all the previous data by using high voltage Ultraviolet light.

这是可以重新编程的内存类型。 我们可以从其中擦除数据并重新编程，即通过使用高压紫外线来擦除所有先前的数据。

• It is required to erase each cell in EPROM.

  需要擦除EPROM中的每个单元。

c) EEPROM (Electrically erasable programmable read only memory)

c)EEPROM(电可擦可编程只读存储器)

The data can be erased and reprogrammed by applying an electric charge. There is no need for ultraviolet light and we can erase only portions of the chip.

可以通过施加电荷来擦除和重新编程数据。 不需要紫外线，我们只能擦除部分芯片。

• It was a replacement for PROM and EPROM chips and later it is used for computer's BIOS.

  它是PROM和EPROM芯片的替代品，后来用于计算机的BIOS。

• Configurations parameters are stored by using EEPROM. In modern computers, they replaced BIOS CMOS memory.

  配置参数通过使用EEPROM存储。 在现代计算机中，它们取代了BIOS CMOS内存。

• It is required that data to be written or erased by EEPROM one byte at a time.

  要求数据一次由EEPROM写入或擦除一个字节。

翻译自: https://www.includehelp.com/operating-systems/types-of-computer-memory.aspx

计算机操作系统 内存