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Memory Types •PROM(Programmable Memory) •RAM (Random Access Memory) Common memory types •DRAM (Dynamic RAM) •SRAM (Static RAM ) •NVRAM (Non-Volatile RAM) •Flash memory 非易失性的 •EPROM(Erasable-andProgrammable Memory) •EEPROM(ElectricallyErasable-andProgrammable Memory) 10.1 Read-Only Memory(1) 10.1.1 Introduction 固件 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. Return Next 10.1 Read-Only Memory(2) 10.1.2 ROM Types 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. 非易失性的 •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. Return Back Next 10.1 Read-Only Memory(3) 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 乍一看which contains all done using a “ROM-Mask” 不可还原的 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. 安全的 使气馁, 阻碍 10.1 Read-Only Memory(4) 10.1 Read-Only Memory(5) 10.1 Read-Only Memory(6) 10.1 Read-Only Memory(7) 10.1 Read-Only Memory(8) Return Back