Learn the types of memory in the market

Memory is the place to store data for the computer to perform tasks, divided into two main streams: temporary memory (RAM, DDR .) and permanent memory (flash, SSD) without data loss when power is off.

Temporary memory

RAM is internal memory, storing only the data needed to perform the task and this information will be lost when there is no power, different from the hard drive (the information remains when the power is turned off). The larger the RAM capacity, the more space there is to manage the program running on the computer and therefore, the PC becomes versatile and works faster.

Currently, besides pushing memory capacity up to 1 GB, 2 GB ., manufacturers also use the technology on the motherboard to divide the 2 channels into RAM, meaning that the data has two "paths" to transmit to chip. " The dual-channel module sends signals to the processor at the same time, " said Marc Bernier, a Kingston expert. " Therefore, the overall bandwidth is increased ".

Cosair DDR2-400 and DDR2-667.Photo: Tomshardware .

Thus, when using the mainboard with a chipset that supports "dual channel", users plug 2 512 MB RAM modules of the same type into the correct slot, the computer speed may be higher than a 1 GB RAM.

In addition, the DDR standard (Double Data Rate) is a method of boosting the data transfer rate of RAM without changing the front-side bus (high-speed data line between chip and memory). main).

For example, when data is transmitted 64 bits / time, the memory chip will give the transmission rate according to the formula: Speed ​​of [clock pulse x 2 (speed doubling effect) x 64 (number of bits transmitted )) / 8 (bit number of bytes). Therefore, a memory chip with DDR - 200 100 MHz standard will give maximum data transfer rate of 1,600 MB / sec.

After that, DDR was upgraded to DDR2, DDR3, DDR4 standards with the ability to speed up exponentially. For example, DDR2 stores data in cells that are activated by using clock pulses to synchronize operation with the data bus. Like DDR, memory cells in the DDR2 standard transmit information based on the clock's up and down amplitude (called double pumping technique). The difference between these two standards is that in DDR2, the bus is pushed to twice the speed of the memory cells, so 4 words of data are transmitted in a memory ring. Therefore, without improving the memory itself, DDR2 can operate twice as fast as the DDR.

Currently, DDR and DDR2 are widely used for system memory, while DDR3, DDR4 usually appear in the memory of high-end graphics cards.

Standard name Clock pulse Bus pulse Data transmission bit / sec DDR2-400 100 MHz 200 MHz 400 million DDR2-533 133 MHz 266 MHz 533 million DDR2-667 166 MHz 333 MHz 667 million DDR2-800 200 MHz 400 MHz 800 million DDR2 -1066 266 MHz 533 MHz 1066 million Module name Clock pulse Memory type Maximum transmission speed PC2-3200200 MHzDDR2-4003.2 GB / sec PC2-4200266 MHzDDR2-5334,264 GB / sec PC2-5300333 MHzDDR2-6675,336 GB / secondPC2-6400400MHzDDR2-8006.4 GB / sec PC2-8500533 MHzDDR2-10668.5 GB / sec

Flash technology

Not only is RAM support technology on the rise, the USB memory market is also thriving. Inside the compact USB drive is a flash storage method.

Microsoft has developed a USB memory card system to speed up the internal memory of a Windows Vista-based computer. Vista's Ready Boost feature will use the free space of flash memory as a virtual memory (similar to the File page on the hard disk), which supports the transfer of frequently accessed files to the flash memory in the USB memory stick to the system. System runs faster.

Solid state memory SSD

Flash memory manufacturers such as SanDisk and Samsung are using semiconductor technology to develop devices that replace mechanical and magnetic drives, called Solid State Disk (SSD).

" Solid-state disks are actually devices that include flash multimedia and a driver, with no moving parts, " said SanDisk expert Doreet Oren. " When using a flash disk, users do not have to worry because the delay is often found in devices with normal read-write data such as hard drives ".

According to manufacturers, the SSD disk is theoretically capable of operating hundreds of times more than a hard drive because there is no need to scan every memory to download a file. The advantage of SSD is durable (because it does not contain mechanical structures), faster, quieter and lighter than other storage products.

However, this type of disc is expensive and takes time to become more popular.