![]() ![]() Such pocketable recorders are far smaller than conventional pocketable recorders, and batteries last far longer. Flash memory is also used in pocketable recorders that record voice without microcassettes, i.e., without mechanical drives. Flash memory is also used in cellular phones, where the identification of the owners and programs are stored and updated by wireless transmission. In digital cameras, photographic images are stored in flash memory. #MEMORY NOTE 3 PORTABLE#Flash memory is widely used as credit-card-sized memory cards, which are called PCMCIA (personal computer memory card international association), for portable computers, as handy memory extensions. Flash memory is used in upgradable BIOS (Basic Input Output System), which is the hardware part of an operating system of some personal computers, and also in modems. Flash memory has many unique applications. In contrast, a flash memory in power-down mode consumes only a few microamperes. A hard disk consumes a few amperes at the start and then consumes tens of milliamperes for rotation after that. Also, flash memory works with far less power consumption, and accordingly if flash memory is installed in a notebook computer, replacing a hard disk, then batteries last far longer. Flash memory is immune to vibration, dust, and mechanical shocks. Currently, we can repeat writing close to a million times and this is three orders of magnitude smaller than hard disks.įlash memory is cheaper with greater memory capacity than DRAM and yet faster, though more expensive per bit, than hard disks. If writing is repeated many times, flash memory gradually requires longer writing time and eventually stops working because of fatigue. Erasure and writing time in both types is a few microseconds, being far slower than RAMs, but is far faster than hard disks whose writing time is tens of milliseconds.įlash memory has one serious shortcoming. #MEMORY NOTE 3 WINDOWS#Reading time in NOR-type flash memory is about hundreds of nanoseconds or less, being comparable to ROMs, but is faster than the NAND-type, though its area is larger (because of more contact windows which occupy large areas). A NAND-type flash memory is illustrated in Fig. White circles denote contact windows between aluminum lines and drains. Applying appropriate voltages to S, D i and A j, writing, reading, or erasure is done. ![]() ![]() All sources of MOSFETs with floating gates are connected to S, which means a source. A 1, A 2, … , A K are the outputs of a memory address decoder, which are connected to the gates of MOSFETs with floating gates and only one of which has a high voltage when the decoder is active. All these lines are connected to the drains of MOSFETs with floating gates. If one memory word consists of 8 bits, we have bit lines, D 1, D 2, … , D 8. A NOR-type flash memory is illustrated in Fig. The first two types have been widely used. They are NOR type, NAND type, AND type, and DINOR type. A flash memory is currently structured in at least four different ways with different features. ![]()
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