Definition and Types of RAM

Definition of RAM

Understanding RAM - RAM (Random Access Memory) is a computer hardware responsible for storing data. RAM is temporary means that stored data can be erased. Unlike the case with the ROM, ROM has duties similar to RAM but the ROM is permanent in the sense that the stored data we can not remove. RAM is a type of memory whose contents can change-change for computers that have the nature of life and can remember data or programs on condition that the electric current and can store and retrieve data very quickly.

Types of RAM RAM and History

History of RAM
History of RAM - RAM (Random Access Memory) invented by Robert Dennard and produced on a large scale by Intel in 1968. From the beginning until now RAM has undergone many changes. Starting from the shape, capacity, speed, and technology at the existing RAM is much different from the initial generation of RAM
Types of RAM
Types of RAM - Some type of RAM that we know today, such as:

1. RAM

Was first discovered by Robert Dennard, in large-scale production in 1968, and this is where history begins ram. RAM requires a voltage of 5.0 volts to be able to run at a frequency of 4.77 MHz, with the memory access time (access time) approximately 200ns (1ns = 10-9 seconds). This first generation of RAM using 30 pin slot on the motherboard.

2. DRAM
IBM creates a DRAM memory on the frontage in 1970, its own DRAM stands for Dynamic Random Access Memory, DRAM has a varied work frequencies, ie between 4.77 MHz to 40MHz.

3. FPM DRAM
This type of memory works like an index or table of contents. Meaning Page itself is part of the memory address contained in a row. When the system requires the contents of a memory address, FPM simply take information about them based on an index that has been owned. FPM allows for faster data transfer on the line (row) of the same from the previous memory type. FPM works in the frequency range 16MHz to 66MHz with 50ns access time around. Additionally FPM can process data transfer (bandwidth) of 188.71 Mega Bytes (MB) per second. FP RAM was discovered around 1987. Memory is used by the system based on the Intel 286, 386 and 486 bit.

4. EDO DRAM EDO
DRAM (extended data output dynamic random access memory) was created in 1995. Memory is a refinement of the FPM, EDO read cycle can shorten it so that it can improve the performance of about 20 percent. EDO has access time is quite varied, which is about 70ns to 50ns and works at a frequency of 33MHz to 75MHz. Although EDO is a refinement of the FPM, but both can not be installed simultaneously, because of differences in ability. Intel 486-compatible with earlier generation Pentium is a database system that uses EDO DRAM. Slot used on the motherboard has a 72 pin.


5. SDRAM
Kingston SDRAM created at the turn of the year 1996-1997, this module can work at a speed (frequency) of the same bus / sync with the working frequency of the processor. SDRAM is then better known as PC66 because it works on a 66MHz bus frequency. Unlike previous memory type that requires a fairly high working voltage, SDRAM only requires a voltage of 3.3 volts and has an access time of 10ns.Selang within a year after PC66 produced and used en masse, Intel makes the new standard type of memory which is the development from PC66 memory. Using the working voltage of 3.3 volts, PC100 memory has an access time of 8ns, shorter than PC66. Additionally PC100 memory can divert the amount of data per detiknya.Selain 800MB PC800 RDRAM memory developed in 1999, SDRAM memory has not been abandoned, even by the Vikings, even more enhanced abilities. As the name implies, PC133 SDRAM memory works at 133MHz bus frequency with an access time of 7.5 ns and was able to stream data at 1.06 GB per second. Although it was developed to work on the PC133 bus frequency 133MHz, and the memory is also capable of running at 100MHz bus frequency, although not as good as the capabilities of the PC100 SDRAM memory at frequencies tersebut.Perkembangan increasingly become - so after Mushkin, in 2000 successfully developed the memory chip able to work at a frequency of 150MHz bus, even though there is no official standard regarding the frequency of the system bus or chipset of this magnitude. Still with a working voltage of 3.3 volts, PC150 memory has an access time of 7ns and able to stream data at 1.28 GB per second. Memory is intentionally created for the purposes of overclockers, but the user gaming applications and 3-D graphics, desktop publishing, and computer servers can take advantage of the presence of PC150 memory. Slot used on the motherboard has a 168 pin.

6. DR RAM
In 1999, Rambus creates a memory system with a new architecture and a revolutionary, totally different from SDRAM.Oleh Rambus memory architecture, memory is called Direct Rambus Dynamic Random Access Memory. By simply using a voltage of 2.5 volts, which works on RDRAM 800MHz system bus via a bus system called Direct Rambus Channel, able to stream data at 1.6 GB per second! Still in the same year, Rambus also develops a memory type other with the same capabilities as DRDRAM. The difference lies only in the working voltage is needed. If DRDRAM requires a voltage of 2.5 volts, the PC800 RDRAM work on voltage 3.3 volt.

7. DDR SDRAM
In 2000, Crucial SDRAM memory has developed the ability to be 2-fold. The technique used is to use the full one wave frequency. If the regular SDRAM only do the instructions on the positive wave, the DDR SDRAM running instruction both on the positive wave and a negative wave. Because of it's memory called DDR SDRAM which stands for Double Data Rate Synchronous Dynamic Random Access Memory. With DDR SDRAM memory, system bus with a frequency of 100-133 MHz will work effectively at a frequency of 200-266 MHz. DDR SDRAM was first used in ultra high-speed AGP graphics card. While the use of the processor, AMD ThunderBird was the first to use it. Slot used on the motherboard has a 184 pin.

8. DDR3 SDRAM
DDR3 RAM has a power requirement is reduced by approximately 16% compared to DDR2. This is because DDR3 is already using 90 nm technology so konsusmsi 1.5v power is required, much less when compared to DDR2 and DDR 2.5V 1.8v. In theory, the speed of which is owned by the RAM is quite riveting. He was able to transfer data at an effective clock of 800-1600 MHz. DDR3 has an internal clock 400-800 MHz, DDR2 is much higher than the 200-533 and 100-300 MHz for DDR. The prototype of DDR3 has 240 pins. It's actually been introduced long ago in early 2005. However, the product itself is really emerged in mid-2007 along with a motherboard that uses the Intel P35 chipset and the motherboard Bearlake supports DDR3 slots. Slots used in motherboards have the same number of pins DDR2 SDRAM slot, but the position is different notchnya so it should not be able to install the module in the slot DDR3 SDRAM DDR2. This was intentionally done because the electrical module with DDR2 DDR2 have different voltages.

9. SO-DIMM

Small Outline Dual In-Line Memory Module (SO-DIMM) is a type of memory used in notebook devices. Physical form roughly half of the regular DDR that can save more space which is very valuable on mobile devices such as notebooks. SO-DIMM generation developments generally in line with the development of RAM for desktop computers. When launched commercially DDR3 SDRAM, DDR3 SO-DIMM also launched. The module uses a slot that has 204 pins. Less than the DDR3 SDRAM.


Components of RAM

Components of RAM - Here are some important components of RAM we need to know, including:
 Type describes the type (variation) of RAM based on the technology it uses, such as SDRAM, DDR or DDR2. It is sometimes also referred to as the "interface". Example: Visipro DDR 256Mb DDR PC266 means using technology.
Capacity describes how much RAM data storage capacity in units of Gigabyte (GB) or megabytes (MB). Capacity is an important factor in the RAM because fungsiny as data storage. Example: 512Mb DDR2 PC4300 Visipro means having a capacity of 512 Megabytes.
 FSB (Front Side Bus stands), which is the data path between the processor dam RAM in units of Megahertz. FSB Processor and RAM unit should have the same number so that data can be transferred optimally [View the table of Dual Channel RAM]. Example: 256MB PC3200 DDR2 Visipro means having a FSB of 400MHz (PC3200 divided by 8 bytes).
Function, explaining the function of RAM, such as Unbuffered (used on the Desktop), ECC, or Registered (both are used on the Server). [See the segment What is Unbuffered, ECC and Registered?] Unbuffered RAM is a common type that is used by computers in general, ECC (Error Correction Code) commonly used in computer Workstation / Low End Server & ECC Registered commonly used on Medium to High End Server. Example: Visipro DDR2 1GB PC4300 ECC Registered ECC Registered means to have a function in the module.
Bandwidth is the amount of data that can be transferred or processed in one second (unit of MB / s or megabytes per secon). Generally at this time include bandwidth DDR/DDR2 RAM RAM Module. Bandwidth can be obtained from the multiplication FSB x Architecture. RAM architecture is 64-bit (8byte), so if DDR PC266 has 266 MHz FSB with 266 MHz x 8 bytes = 2100 MB / s. This means that the DDR PC266 (FSB) with DDR PC2100 (Bandwidth). Example: 512MB PC4300 DDR2 Visipro means to have a bandwidth of 4300MB / s.
The number tells you how many IC chip (IC) mounted on a RAM module. The fewer the number of IC, the higher the density (capacity per-IC). Generally it is 4, 8, 16 IC (the standard RAM). At ECC RAM IC has a number 9 & 16, and the ECC Registered had IC number 9 & 16 plus 1 that functions as a Registered ICC. Example: 256MB DDR Visipro can have 4, 8 or 16 IC. When using 4IC mean density IC = 64MB, 32MB & 8IC = 16IC = 16MB.

RAM Timing


RAM Timing - Timing the RAM is RAM size of the time delay that occurs when the processor attempts to access data in RAM. This happens because modern processors currently have the working frequency is much faster than RAM. Timing is one measure that determines the speed of the RAM module in addition to bandwidth. Increasingly stringent timing and the more RAM the maximum bandwidth that can be achieved, the faster the performance of RAM. But of course these two aspects are usually the opposite, if you want to get the timing is tight, we have to lower the bandwidth for your computer to remain stable. Vice versa, to achieve higher bandwidth, timing should be made more modern RAM modules longgar.Pada current, usually supplied Serial Presence Detect (SPD), which contains RAM timing settings are automatically suggested by the manufacturer on a specific operating frequency. However, computer users can set it manually through the settings in the BIOS. This is most often done when overclock RAM in order to achieve the highest possible bandwidth with timings as tight as possible. There are 5 types of RAM timings most frequently altered by overclockers because it has the greatest impact on performance and stability, namely:

1. CAS Latency (CL)
CAS Latency is the time delay that occurs when the memory controller ordered the RAM to access the data lies in a specific row and column until the data reaches the pin that is on the RAM module that can be directly transferred to the processor.

2. tRCD (Row Address to Column Address Delay Time)
tRCD is the number of clock cycles required to open the lines of memory and access the column contained therein.

3. tRP (Row Percharge Time)
tRP is the number of clock cycles needed to precharge command to the next line access memory.

4. tRAS (Row Access Strobe Time)
tRAS is the number of clock cycles required between the bank active command and precharge command. Usually the amount is the sum of the CL + tRCD + tRP.

5. Command Rate (CR)
Command Rate is the number of clock cycles required to find the first row of data you want dicari.Biasanya on a RAM module, written in a format timings CL-tRCD-tRP-tRAS CR. For example, a module with a capacity of 2GB DDR2 ram which works on 800 MHz frequency requires voltage 1.8 V and has a CL 5, tRCD 5 tRP 5 tRAS 15 and CR 1T, the ram module specification will be written: 2048MB PC6400 DDR-2 5 - 5-5-15 1T v 1.8.

How it Works RAM

How it Works-RAM When we turn on the computer, the first working device is the Processor. Processor serves as a data processor and request data from storage, the Hard Disk (HDD). This means that data is sent from the Hard Disk after a request from the processor.

But in practice this is difficult because of differences in technology between Processor and Hard Disk. Processor alone is pure digital components, and will process data very quickly (the highest bandwidth currently P4 6.4 GB / s with FSB 800MHz). Hard Disk While most of the technology is certainly quite slow mechanical than digital (Bandwidth or Transfer Rate Serial ATA HDD ranges 150 MB / s). Theoretically, the data processor speeds ranging from 46X faster than HDD. That is, if the processor waiting for data from the HDD supply will be "Bottle-Neck" very severe.

To overcome this situation, it is necessary device Main Memory (Primary Memory) or called RAM. RAM stands for Random Access Memory. RAM Processor serves to assist in the provision of data "super fast" required. RAM works just like Digital HDD, RAM since all components are already using digital technology. With RAM, the processor does not need to wait for shipment data from the HDD. Currently has a bandwidth of DDR2 RAM 3.2 GB / s (PC400), so as not to disturb the current supply Motherboard Dual Channel technology which can double the bandwidth to 2x increase to 128-bit architecture. That means, 2-chip DDR2 Dual Channel mode can supply the right amount of data to the processor (3.2 GB / sx Dual Channel = 6.4 GB / s).


A few articles Types of RAM and RAM from my understanding.