Takes the same amount of time to access regardless where it is stored in memory
As opposed to magnetic tapes used in earlier computer where the further along, the longer it took
Static RAM (SRAM)
Integrated circuits that are memory arrays with (usually) a single access port that can be used to read or a write
Data is stored in flip flops (holds data as long as power is surprised)
Requires 6 transistors
Fixed access time to any datum, though differing read and write speeds
Cannot be built the same way we build Register File because the scale is beyond that of multiplexers so it outputs the stored values encoded using three-state buffers
Dynamic RAM (DRAM)
Data is stored as charges in a capacitor
Accessed (read or write) using a single transistor
Much cheaper and denser than SRAMs
Slower to access than SRAM
Dynamic = Must be periodically refreshed
Because the charge in the capacitor will fade
Most of the time done by reading and then rewriting a row at a time
Modern DRAM does that on it’s own
Uses a two level decoder with row access and column access
Moves a row into a buffer and then accesses the column from there
If multiple reads from a single row happens, it does not need to pull it out every single time
That optimizes things because you are most likely to access sequential data
