MEMORY DEVICES
FLEXIBLE DISCS: Input-output device. There are two types according to their diameter, those of 51/4 and those of 31/2, these measurements are expressed in inches (13.3 and 8.8 centimeters). In the two types there are, storage capacity seconds, two groups: the double-sided-double density (DD) and the double-sided-high density (HD), the storage capacities are as follows:
HARD DISKS: Input-output devices. It differs from flexible in capacity, access speed in the fact that it is not transportable (removable), but is connected (in most cases) to the inside of the computer. The capacities of the access times of the hard disks are diverse, in terms of capacity they vary between 20 Mb (currently out of date), 40 Mb, 60 Mb, 80 Mb, 120 Mb, 170 Mb up to 550, 720, 1 GigaByte or more (discs of up to 18 GB are currently offered). Access times also vary and are measured in milliseconds.
Optical Discs: Input-output device. These devices use laser technology to record the data. They have a large storage capacity of the order of Gigabytes (1 Gigabyte = 1024Mb- about one billion bytes).
Streamers: Input-output device. They are devices that use magnetic tapes to store data. They have a large storage capacity. Due to its slow access speed, its use is basically restricted to storage.
TYPES OF MEMORY
1.-Types of RAM Memory
* DRAM (Dynamic Random Access Memory): It is the working memory, also called RAM, is organized in directions that are replaced many times per second. This memory reached speeds of 80 and 70 nanoseconds (ns), this is the time it takes to empty one direction to be able to enter the next, the lower the number, the higher the speed, and was used until the time of the 386 teams.
* FPM (Fast Page Mode): The name of this memory comes from the way it does data transfer, which is also called fast paging. Until about a year ago this memory was the most popular, it was the normal type of memory for computers 386, 486 and the first Pentium®, it came to be manufactured at speeds of 60ns and the way they presented was in SIMM 30-pin modules, for the 386 and 486 equipment and for the Pentium® equipment it was in 72-pin SIMM.
* EDO (Extended Data Output): This memory was an innovation in terms of data transmission and could reach speeds of up to 45ns, leaving users satisfied. The transmission was made by blocks of memory and not by instruction as it had been doing FPM memories. It is used in computers with Pentium® processors, Pentium Pro® and the first Pentium II®, in addition to its high compatibility, they have a low price and it is a viable option for these devices. Your presentation can be in SIMM or DIMM.
* SDRAM (Synchronous DRAM): This memory works as its name indicates, it is synchronized with the clock of the processor obtaining information in each clock cycle, without having to wait as in the previous cases. The SDRAM memory can accept BUS speeds up to 100Mhz, which reflects a very good stability and reach speeds of 10ns. They are presented in DIMM modules, and due to their 64-bit transfer, it is not necessary to install it in pairs.
* RDRAM (Rambus DRAM): This memory has a data transfer of 64 bits that can be produced in bursts of 2ns, it can also reach a transfer rate of 533 MHz with peaks of 1.6Gb / s. Very soon it will reach domain in the market, since it will be used in computers with the new Pentium 4® processor. It is ideal since it avoids the bottlenecks between the AGP graphics card and the system memory, nowadays you can find this type of memories in the NINTENDO 64® consoles. It will be launched to the market by SAMSUNG® and HITACHI®.
2.-Types of ROM Memory
* EPROM (Erasable Programmable Read-Only Memory): Used to correct last minute errors in the ROM, the user can not modify it and can be deleted exposing the ROM to an ultraviolet light.
* EEPROM (Electrically Erasable Programmable Read-Only Memory): This memory can be erased and re-programmed by means of an electrical load, but only one byte of information can be changed at a time.
* FLASH MEMORY: It is a type of EEPROM memory that is reprogrammable, its use is usually in BIOS hence its name.
Other types of RAM
* BEDO (Burst Extended Data Output): It was designed to achieve higher BUS speeds. It works in the same way as the SDRAM, that is, the data transfer is done in each clock cycle, but this memory does it in burst, making the delivery times disappear almost completely.
* DDR SDRAM (Double Data Rate SDRAM or SDRAM-II): This memory will have the same appearance as a DIMM, but the difference will be that it will have more pins, going from 168 pins of the current DIMM to 184 pins, besides having only one notch on the tablet. Seeing a little voltage, the DDR will work with only 2.5V, this being a reduction of 30% compared to the current 3.3V of the SDRAM. It will work at speeds of 200Mhz.
* VRAM: It's like normal RAM, but the difference is that it can be accessed at the same time by the monitor and the processor of the video card, you can read and write it at the same time.
* SGRAM (Synchronous Graphic RAM): It offers the same capabilities of SDRAM memory but for graphics cards, it is used in new 3D accelerator graphics cards.
As we can see, speaking from memory is not easy and its field is not limited, on the contrary as all technologies are advancing day by day, and if we ever think that speaking by heart is something basic, with this we can realize that memory is not just a tablet with soldered chips, it is a technology that is up to date as well as all the computational technology.