Dual-ported RAM (DPRAM) is a type of
random-access memory
Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written in almost the ...
that allows multiple reads or writes to occur at the same time, or nearly the same time, unlike single-ported RAM which allows only one access at a time.
Video RAM or
VRAM is a common form of dual-ported
dynamic RAM
Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxid ...
mostly used for video memory, allowing the
CPU
A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, a ...
to draw the image at the same time the video hardware is reading it out to the screen.
Apart from VRAM, most other types of dual-ported RAM are based on
static RAM
Static random-access memory (static RAM or SRAM) is a type of random-access memory (RAM) that uses latching circuitry (flip-flop) to store each bit. SRAM is volatile memory; data is lost when power is removed.
The term ''static'' differe ...
technology.
Most CPUs implement the
processor register
A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-only. ...
s as a small dual-ported or multi-ported RAM (see
Register File
A register file is an array of processor registers in a central processing unit (CPU). Register banking is the method of using a single name to access multiple different physical registers depending on the operating mode. Modern integrated circuit- ...
).
Computer memory
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