RAM (Random Access Memory) Types and Functions

Posted on Aug 2, 2024 in Computers

RAM (Random Access Memory) is a type of memory that can be accessed randomly, meaning you can access any byte of memory without going through the preceding bytes. RAM is the most common type of computer memory and other devices such as printers.

Types of RAM

There are two basic types of RAM:

  • DRAM (Dynamic RAM)
  • SRAM (Static RAM)

The two types differ in the technology used to store data. Dynamic RAM needs to be refreshed thousands of times per second while static RAM does not need to be refreshed as often, making it faster but also more expensive than dynamic RAM.

Specific RAM Types

  • VRAM (Video RAM): A special-purpose memory used by video adapters. Unlike conventional RAM, the VRAM can be accessed by two different devices simultaneously
  • SIMM (Single In-line Memory Module): A type of packaging consisting of a small printed circuit board that holds memory chips, which are inserted into a SIMM socket on the motherboard or memory board.
  • DIMM (Dual In-line Memory Module): A type of packaging, consisting of a small printed circuit board that holds memory chips, which is inserted into a DIMM socket on the motherboard and generally uses a 168-pin connector.
  • DIP (Dual In-line Package): Packaging type consisting of a memory chip storing a rectangular box with two rows of connecting pins on each side.
  • RAM Disk: Refers to RAM that has been configured to simulate a hard disk. You can access the files in a RAM disk the same way in which access to a hard disk. Vdisk, short for virtual disk, another name for RAM Disks.
  • Cache or RAM cache: A cache is a special high-speed storage. Can be either a reserved area of main memory as a storage device independent high speed. There are two types of cache frequently used in personal computers: memory caching and disk caching.
  • SRAM (Static Random Access Memory): A type of memory that is faster and more reliable than the more common DRAM (Dynamic RAM). The term static is derived from the fact that needs to be refreshed less often than dynamic RAM. The SRAM, due to its high speed, is used as cache memory.
  • DRAM (Dynamic Random Access Memory): Memory type of large capacity but needs to be constantly refreshed (re-energized) or lose their contents. Generally uses a transistor and a capacitor to represent a bit capacitors must be energized hundreds of times per second to keep the charges.
  • SDRAM (Synchronous DRAM): Synchronous DRAM, a type of dynamic RAM which is almost 20% faster than EDO RAM. SDRAM linking two or more arrays of internal memory so that while it is accessing an array, the next is being prepared for access.
  • FPM (Fast Page Mode): Memory in paged mode, the most common design of dynamic RAM chips. Access to the memory bits is done by means of coordinates, row and column.
  • EDO (Extended Data Output): A type of dynamic RAM chip that improves the performance of Fast Page Mode memory about 10%.
  • PB SRAM (Pipeline Burst SRAM): Is called ‘pipeline’ to a category of techniques that provide a simultaneous process, or in parallel within the computer, and refers to overlapping operations by moving data or instructions in a ‘pipe’ conceptual with all phases of the ‘pipe’ processed simultaneously. For example, while one instruction is being executed, the computer is decoding the next instruction.
  • SDR SDRAM: Synchronous memory with access times of 25 to 10 ns and presented in 168-pin DIMMs.
  • DDR SDRAM: Synchronous Memory, sends data twice per clock cycle. This works at twice the speed of the system bus without increasing the clock frequency. It comes in 184-pin DIMMs
  • DDR2 SDRAM: DDR-2 memories are an improvement of DDR (Double Data Rate), which allow buffers input / output work at twice the core frequency, allowing for each clock cycle, four transfers are made. DIMMs are presented in 240 contacts.
  • DDR3 SDRAM: Considered the successor to the current standard memory DDR 2, DDR 3 promises to deliver significant performance improvements at lower voltage levels, leading to a decline in overall consumption.
  • RDRAM (Rambus DRAM): While competing in the DDR, RDRAM operates very differently: the DDR uses the rising and falling edges of clock to double its effective frequency (up to DDR-400) with a data bus 64-bit , while the frequency increases RDRAM chips to avoid bottlenecks (up PC800) with a data bus of 16 bits.