Common memory types DRAM (Dynamic RAM) RAM (Random Access Memory) NVRAM (Non-Volatile RAM) SRAM (Static RAM ) Flash memory EEPROM(Electrically- Erasable-and- Programmable Memory) EPROM(Erasable-and- Programmable Memory) PROM(Programmable Memory) Memory Types 非易失性的

ReturnNext 10.1 Read-Only Memory(1) Read-only memory (ROM), also known as firmware, is an integrated circuit programmed with specific data when it is manufactured. ROM chips are used not only in computers, but in most other electronic items as well. In this section, you will learn about the different types of ROM and how each works Introduction 固件

10.1 Read-Only Memory(2) ROM Types NextBackReturn There are five basic ROM types: ROM, PROM, EPROM, EEPROM, Flash memory. Each type has unique characteristics, but they are all types of memory with two things in common: Data stored in these chips is nonvolatile -- it is not lost when power is removed. Data stored in these chips is either unchangeable or requires a special operation to change (unlike RAM, which can be changed as easily as it is read). This means that removing the power source from the chip will not cause it to lose any data. 非易失性的

ROM-Memory does not allow for deletion, nor can it be overwritten by the user via program commands. Therefore, all programs and data supposed to be in the ROM have to be installed through the production process. This is done using a “ROM-Mask” which contains all data and is used during the processing of the silicon chip. At first sight, the limitation of the irreversible writing process seems to be a disadvantage. But it also discourages potential attackers to modify the program code on less secure chip cards Read-Only Memory(3) 乍一看 不可还原的 使气馁, 阻碍 安全的

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10.1 Read-Only Memory(8) BackReturn