1.Dynamic Random Access Memory (DRAM)
- Contents are constantly refreshed 1000 times per second
- Access tome 60-70 nanoseconds
2.Synchronous Dynamic Random
Access Memory (SDRAM)
- Quicker than DRAM.
- Access time less than 60 nanoseconds.
3.Direct Rambus Dynamic Random
Access Memory(DRDRAM)
- New type of RAM architecture.
- Access time 20 times faster than DRAM.
- More expensive.
4.Static Random Access Memory(SRAM)
- Doesn't need refreshing.
- Retains contents as long as power applied to the chip.
- Access time around 10 nanoseconds.
- Used for cache memory.
- Also for date and time settings as powered by small battery.
5.Cache Memory
- Small amount of memory typically 256 or 512 kilobytes.
- Temporary store for often used instructions.
- Level 1 cache is built within the CPU (internal)
- Level 2 cache may be on chip or nearby (external)
- Faster for CPU to access than main memory.
6. Video Random Access Memory
- Holds data to be displayed on computer screen.
- Has two data paths allowing READ and WRITE to occur at the same time.
- A system’s amount of VRAM relates to the number of colors and resolution.
- A graphics card may have its own VRAM chip on board.
7. Virtual Memory
- Users backing storage (e.g. hard disk as a temporary location for programs and data where insufficient RAM available)
- Swaps programs and data between the hard-disk and RAM as the CPU requires than for processing.
- A cheap method of running large or many programs on a computer system.
- Cost is speed the CPU can access RAM in nanoseconds but hard-disk in milliseconds.
- Virtual memory is much slower than RAM.