It is used in USBįlash drives, memory cards (in digital cameras, MP3 players, etc.),Īnd in SSDs.
#Random access memory code
System code and on Windows computers for the BIOS program that runs at NOR flash memory is used to store cell phone operating Write data to specific locations, and can reference and retrieve a NOR flash memory provides high-speed random access.
Memory, the basic unit is 16 or 32 bits, and the logical organization Logical organization resembles a NOR logic device. In NOR flash memory, the basic unit of access is a bit, and the There are two distinctive types of flash memory, designated as NOR and It can read and write data to specific locations, and can reference and retrieve a single byte" so, differently from NOR devices, they are random_access. On the other hand, NOR devices "provides high-speed random access. Simply put, this is the answer: NAND flash-based memories can not be considered as random-access because they are not endowed with a random-access external address bus (unlike I thought). Since my doubt could be somebody else's too, I quote Stallings text below. Right after I posted this question, I've read a text from William Stallings ( Computer Organization and Architecture) clarifying my doubt. At the NAND level, the sequential reads take just as long as the random ones, it's just that you can start the next one before the first one finishes. However, this only applies to large-block access, so if you're accessing a specific byte at a time, you won't be able to take advantage of this parallelism anyway. Also, a smart controller can detect that you're doing a sequential workload, and start reading data ahead of what you've asked for yet. The reason SSDs are faster at sequential access than random access has nothing to do with the underlying NAND, but rather its because the controller can always access all NAND dies in parallel, whereas for a random workload this is statistically unlikely. Access speed does not vary at all based on where on the media a particular bit of information is stored. In contrast, with other direct-access data storage media such as hard disks, CD-RWs, DVD-RWs and the older magnetic tapes and drum memory, the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement.īased on this definition, I would argue that YES, SSDs are "true" random-access devices. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory.
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