- Memory: Is just 0’s (off) and 1’s (on); switches representing bits.
- Cache Memory: Closest to the CPU, Fastest, L1 Cache is on the CPU, L2 Cache is connected to CPU but outside it.
- ROM (Read Only Memory) is nonvolatile (retains memory after power loss); most common use is the BIOS.
- PROM (Programmable Read Only Memory):
- Can only be written once, normally at the factory.
- EPROM (Erasable Programmable Read Only Memory):
- Can be erased (flashed) and written many times, by shining an ultraviolet light (flash) on a small window on the chip (normally covered by foil).
- EEPROM (Electrically Erasable Programmable Read Only Memory):
- PLD (Programmable Logic Devices) are programmable after they leave the factory (EPROM, EEPROM and Flash Memory). Not PROM.
- RAM (Random Access Memory) is volatile memory.
- It loses the memory content after a power loss(or within a few minutes).
- This can be memory sticks or embedded memory.
- SRAM and DRAM:
- SRAM (Static RAM): Fast and Expensive.
- Uses latches to store bits (Flip-Flops).
- Does not need refreshing to keep data, keeps data until power is lost.
- This can be embedded on the CPU.
- DRAM (Dynamic RAM) Slower and Cheaper.
- Uses small capacitors. Must be refreshed to keep data integrity (100-1000ms).
- This can be embedded on graphics cards.
- SDRAM: (Synchronous DRAM):
- What we normally put in the motherboard slots for the memory sticks.
- Most common now is DDR (Double Data Rate) 1, 2, 3, 4 SDRAM.
- SRAM (Static RAM): Fast and Expensive.
- RAM (Random Access Memory) is volatile memory.
- PROM (Programmable Read Only Memory):
- ROM (Read Only Memory) is nonvolatile (retains memory after power loss); most common use is the BIOS.
- Cache Memory: Closest to the CPU, Fastest, L1 Cache is on the CPU, L2 Cache is connected to CPU but outside it.
