Explain the Primary Difference Between Random Access Memory (Ram) and Read-only Memory (Rom).
Computer retentivity is a generic term for all of the different types of information storage engineering that a computer may use, including RAM, ROM, and wink retentiveness.
Some types of computer memory are designed to be very fast, meaning that the central processing unit (CPU) can access data stored at that place very quickly. Other types are designed to be very low cost, so that big amounts of information can be stored there economically.
Another way that reckoner memory can vary is that some types are non-volatile, which means they can store information on a long term basis even when there is no power. And some types are volatile, which are often faster, but which lose all the data stored on them as soon as the ability is switched off.
A reckoner arrangement is congenital using a combination of these types of computer memory, and the verbal configuration can exist optimized to produce the maximum data processing speed or the minimum price, or some compromise between the two.
What are the Different Types of Computer Retentiveness?
Although many types of retention in a reckoner exist, the most basic stardom is between primary memory, often called system retentiveness, and secondary memory, which is more commonly called storage.
The key difference between primary and secondary retentiveness is speed of access.
- Primary memory includes ROM and RAM, and is located shut to the CPU on the figurer motherboard, enabling the CPU to read information from primary retentivity very rapidly indeed. It is used to shop information that the CPU needs imminently so that it does not have to wait for information technology to be delivered.
- Secondary memory past contrast, is usually physically located within a separate storage device, such as a hard disk or solid state drive (SSD), which is connected to the calculator system either direct or over a network. The cost per gigabyte of secondary memory is much lower, but the read and write speeds are significantly slower.
Over several periods of computer evolution, a wide of array of computer retentivity types has been deployed, each with its ain strengths and weaknesses.
Primary Memory Types: RAM and ROM
There are two cardinal types of primary retentivity:
- RAM, or random admission retentivity
- ROM, or read-only retentivity
Let's await in-depth at both types of retention.
one) RAM Computer Retentivity
The acronym RAM stems from the fact that data stored in random access memory can exist accessed – every bit the proper noun suggests – in any random order. Or, put some other fashion, any random bit of data tin can exist accessed only equally quickly as any other chip.
The most important things to empathise nearly RAM are that RAM memory is very fast, it can exist written to every bit well as read, it is volatile (and so all data stored in RAM retention is lost when information technology loses power) and, finally, it is very expensive compared to all types of secondary retentiveness in terms of cost per gigabyte. Information technology is because of the relative high cost of RAM compared to secondary retention types that most figurer systems use both chief and secondary memory.
Data that is required for imminent processing is moved to RAM where it tin can be accessed and modified very quickly, so that the CPU is not kept waiting. When the data is no longer required it is shunted out to slower merely cheaper secondary memory, and the RAM space that has been freed up is filled with the adjacent clamper of information that is nearly to exist used.
Types of RAM
- DRAM: DRAM stands for Dynamic RAM, and it is the most common type of RAM used in computers. The oldest type is known as single data rate (SDR) DRAM, only newer computers apply faster dual information rate (DDR) DRAM. DDR comes in several versions including DDR2 , DDR3, and DDR4, which offer improve performance and are more energy efficient than DDR. All the same different versions are incompatible, so it is non possible to mix DDR2 with DDR3 DRAM in a computer system. DRAM consists of a transistor and a capacitor in each cell.
- SRAM: SRAM stands for Static RAM, and it is a particular type of RAM which is faster than DRAM, but more expensive and bulker, having 6 transistors in each prison cell. For those reasons SRAM is generally only used equally a data cache within a CPU itself or as RAM in very high-end server systems. A small SRAM enshroud of the virtually imminently-needed data can issue in meaning speed improvements in a system
The cardinal differences between DRAM and SRAM is that SRAM is faster than DRAM – maybe two to three times faster – just more expensive and bulkier. SRAM is usually available in megabytes, while DRAM is purchased in gigabytes.
DRAM uses more energy than SRAM considering it constantly needs to be refreshed to maintain data integrity, while SRAM – though volatile – does not need abiding refreshing when it is powered up.
2) ROM Computer Retentiveness
ROM stands for read-only retentivity, and the name stems from the fact that while data can exist read from this type of computer retentiveness, data cannot usually be written to it. Information technology is a very fast type of computer retention which is usually installed close to the CPU on the motherboard.
ROM is a type of non-volatile memory, which means that the data stored in ROM persists in the memory even when it receives no power – for example when the reckoner is turned off. In that sense it is like to secondary memory, which is used for long term storage.
When a computer is turned on, the CPU can begin reading data stored in ROM without the need for drivers or other complex software to assist it communicate. The ROM unremarkably contains "bootstrap code" which is the basic set of instructions a calculator needs to carry out to become aware of the operating system stored in secondary memory, and to load parts of the operating arrangement into principal memory and so that information technology tin start upward and become ready to apply.
ROM is too used in simpler electronic devices to store firmware which runs as shortly equally the device is switched on.
Types of ROM
ROM is available in several different types, including PROM, EPROM, and EEPROM.
- PROM PROM stands for Programmable Read-Only Retentivity, and it is different from true ROM in that while a ROM is programmed (i.e. has information written to it) during the manufacturing process, a PROM is manufactured in an empty country so programmed later using a PROM programmer or burner.
- EPROM EPROM stands for Erasable Programmable Read-Only Memory, and as the name suggests, data stored in an EPROM can be erased and the EPROM reprogrammed. Erasing an EPROM involves removing it from the estimator and exposing it to ultraviolet light before re-burning it.
- EEPROM EEPROM stands for Electrically Erasable Programmable Read-Only Retentivity, and the distinction between EPROM and EEPROM is that the latter can be erased and written to past the reckoner system it is installed in. In that sense EEPROM is not strictly read-only. However in many cases the write process is tedious, and then it is unremarkably merely washed to update program code such as firmware or BIOS lawmaking on an occasional basis
Confusingly, NAND flash memory (such as that found in USB memory sticks and solid state disk drives) is a blazon of EEPROM, but NAND flash is considered to exist secondary retentiveness.
Secondary Memory Types
Secondary retentiveness comprises many different storage media which can be straight fastened to a figurer organization. These include:
- hard disk drives
- solid state drives (SSDs)
- Optical (CD or DVD) drives
- Tape drives
Secondary memory also includes:
- Storage arrays including 3D NAND flash arrays continued over a storage area network (SAN)
- Storage devices which may be continued over a conventional network (known as network fastened storage, or NAS)
Arguably cloud storage can likewise exist called secondary memory.
Differences between RAM and ROM
ROM:
- Non-volatile
- Fast to read
- Normally used in small quantities
- Cannot exist written to quickly
- Used to store boot instructions or firmware
- Relatively expensive per megabyte stored compared to RAM
RAM:
- Volatile
- Fast to read and write
- Used every bit arrangement memory to store information (including plan code) that the CPU needs to procedure imminently
- Relatively cheap per megabyte stored compared to ROM, but relatively expensive compared to secondary memory
What Technology is Between Principal and Secondary Memory?
In the last year or so a new retentiveness medium called 3D XPoint has been adult with characteristics that lie between primary and secondary memory.
3D XPoint is more expensive but faster than secondary retention, and lower cost but slower than RAM. It is besides a non-volatile memory type.
These characteristics mean that information technology tin exist used as an alternative to RAM in systems which crave vast amounts of system retentivity that would exist too expensive to build using RAM (such equally systems hosting in-retention databases). The trade-off is that such systems do not enjoy the full performance gains of using RAM.
Since 3D XPoint is not-volatile, systems that utilise 3D XPoint for arrangement memory can be up and running over again after a ability failure or other interruption very chop-chop, without the need for all the information to be read back into organization retentivity from secondary retentivity.
Explain the Primary Difference Between Random Access Memory (Ram) and Read-only Memory (Rom).
Source: https://www.enterprisestorageforum.com/hardware/types-of-computer-memory/
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