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Types of RAM (Ramdom Access Memory)

Types of RAM

There are many different types of RAM which have appeared over the years and it is often difficult knowing the difference between them both performance wise and visually identifying them. This article tells a little about each RAM type, what it looks like and how it performs.

FPM RAM
FPM RAM, which stands for “Fast Page Mode RAMÃ is a type of Dynamic RAM (DRAM). The term "Fast Page Mode" comes from the capability of memory being able to access data that is on the same page and can be done with less latency. Most 486 and Pentium based systems from 1995 and earlier use FPM Memory. 
FPM RAM

EDO RAM
EDO RAM, which stands for "Extended Data Out RAM" came out in 1995 as a new type of memory available for Pentium based systems. EDO is a modified form of FPM RAM which is commonly referred to as "Hyper Page Mode". Extended Data Out refers to fact that the data output drivers on the memory module are not switched off when the memory controller removes the column address to begin the next cycle, unlike FPM RAM. Most early Penitum based systems use EDO. 
EDO RAM

SDRAM
SDRAM , which is short for Synchronous DRAM is a type of DRAM that runs in synchronization with the memory bus. Beginning in 1996 most Intel based chipsets began to support SDRAM which made it a popular choice for new systems in 2001.
SDRAM is capable of running at 133MHz which is about three times faster than FPM RAM and twice as fast as EDO RAM. Most Pentium or Celeron systems purchased in 1999 have SDRAM.
SD RAM

DDR RAM
DDR RAM, which stands for "Double Data Rate" which is a type of SDRAM and appeared first on the market around 2001 but didn’t catch on until about 2001 when the mainstream motherboards started supporting it. The difference between SDRAM and DDR RAM is that instead of doubling the clock rate it transfers data twice per clock cycle which effectively doubles the data rate. DDRRAM has become mainstream in the graphics card market and has become the memory standard.
DDR RAM

DDR2 RAM
DDR2 RAM, which stands for "Double Data Rate 2" is a newer version of DDR which is twice as fast as the original DDR RAM. DDR2RAM came out in mid 2003 and the first chipsets that supported DDR2 came out in mid 2004. DDR2 still is double data rate just like the original DDR however DDR2-RAM has modified signaling which enables higher speeds to be achieved with more immunity to signal noise and cross-talk between signals.
DDR2 RAM

RAMBUS (RIMM) RAM
RAMBUS RDRAM is a type of ram of its own, it came out in 1999 and was developed from traditional DRAM but its architecture is totally new. The RAMBUS design gives smarter access to the ram meaning that units can prefetch data and free some CPU work. The idea behind RAMBUS RAM is to get small packets of data from the RAM, but at very high clock speeds. For example, SD RAM can get 64bit of information at 100MHz where RAMBUS RAM would get 16bits of data at 800MHz. RIMM ram was generally unsuccessful as Intel had a lot of problems with the RAM timing or signal noise. RD RAM did make an appearance in the Sony Playstation 2 and the Nintendo 64 game consoles. 
RD RAM


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Types of ROM (Read-Only-Memory)

Types of ROM (Read-Only-Memory)

As you may already know ROM is read only memory. This means that the processor can only read the memory on the ROM but cannot write memory on it. This is done so that the memory on the ROM is not lost as it may contain vital system information.
 

Now as regards to your question, there are namely 4 types of ROM:-

* ROM (Read Only Memory)
This is your normal ROM that is found in most PC's. It is designed similar to a processor, and is made out of silicon. Data can be read from it but you cannot write data on it. This is the permanent memory of the system. It is used to perform a single function.

* PROM (Programmable ROM)
PROM is programmable ROM. Sometimes we may want to write some data on the ROM. In such cases we use PROM. Data can be written on it using special equipment. It is important to note that data can be written on PROM only once but it cannot be removed from the PROM.

* EPROM (programmable ROM from which data can be programmed and erased)
EPROM is programmable ROM from which data can be programmed and erased. Note that programming and erasing is not limited to just one time. It is done using ultra violet light. The downside to this that i requires additional hardware to program it. EPROM is now used in most bios systems. This provides flexibility for the programmer.

* EEPROM (Extension of EPROM)

EEPROM is the next generation of ROM. It takes EPROM to the next level. As compared to EPROM, EEPROM can be programmed using software technology. The user himself can program the ROM using system software. The main advantage of this is you don't need special hardware to program it. This saves the programmer a lot of money. This has become the dominating force in the BIOS ROM market. Majority of the motherboards these days come with EEPROM.
 
 
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