| Every computer comes with a certain amount of | | | | Almost all systems used to ship with 3.3 volt, 168-pin |
| physical memory, usually referred to as main memory | | | | SDRAM DIMMs. SDRAM is not an extension of older |
| or RAM. You can think of main memory as an array | | | | EDO DRAM but a new type of DRAM altogether. |
| of boxes, each of which can hold a single byte of | | | | SDRAM started out running at 66 MHz, while older |
| information. A computer that has 1 megabyte of | | | | fast page mode DRAM and EDO max out at 50 MHz. |
| memory, therefore, can hold about 1 million bytes (or | | | | SDRAM is able to scale to 133 MHz (PC133) officially, |
| characters) of information. | | | | and unofficially up to 180MHz or higher. As processors |
| Types Of RAMs And Its Uses The type of RAM | | | | get faster, new generations of memory such as DDR |
| doesn't really matter but using plain old SDRAM | | | | and RDRAM are required to get proper performance. |
| memory might slow you down. Discussed below are | | | | DDR (Double Data Rate SDRAM) |
| the types of RAMs its uses. | | | | DDR basically doubles the rate of data transfer of |
| FPM RAM | | | | standard SDRAM by transferring data on the up and |
| FPM RAM, which stands for Fast Page Mode RAM is | | | | down tick of a clock cycle. DDR memory operating at |
| a type of Dynamic RAM (DRAM). The term Fast | | | | 333MHz actually operates at 166MHz * 2 (aka PC333 |
| Page Mode comes from the capability of memory | | | | PC2700) or 133MHz*2 (PC266 / PC2100). DDR is a |
| being able to access data that is on the same page | | | | 2.5 volt technology that uses 184 pins in its DIMMs. It is |
| and can be done with less latency. Most 486 and | | | | incompatible with SDRAM physically, but uses a similar |
| Pentium based systems from 1995 and earlier use | | | | parallel bus, making it easier to implement than |
| FPM Memory. | | | | RDRAM, which is a different technology. |
| EDO RAM | | | | Rambus DRAM (RDRAM) |
| EDO RAM, which stands for Extended Data Out | | | | Despite it's higher price, Intel has given RDRAM it's |
| RAM came out in 1995 as a new type of memory | | | | blessing for the consumer market, and it will be the |
| available for Pentium based systems. EDO is a | | | | sole choice of computer memory for Intel's Pentium 4. |
| modified form of FPM RAM which is commonly | | | | RDRAM is a serial memory technology that arrived in |
| referred to as Hyper Page Mode. Extended Data Out | | | | three flavors, PC600, PC700, and PC800. PC800 |
| refers to fact that the data output drivers on the | | | | RDRAM has double the maximum throughput of old |
| memory module are not switched off when the | | | | PC100 SDRAM, but a higher latency. RDRAM designs |
| memory controller removes the column address to | | | | with multiple channels, such as those in Pentium 4 |
| begin the next cycle, unlike FPM RAM. Most early | | | | motherboards, are currently at the top of the heap in |
| Penitum based systems use EDO. | | | | memory throughput, especially when paired with |
| SDRAM (Synchronous DRAM) | | | | PC1066 RDRAM memory. |