A datapath is a collection of

functional unit In computer engineering, an execution unit (E-unit or EU) is a part of the central processing unit (CPU) that performs the operations and calculations as instructed by the computer program. It may have its own internal control sequence unit (not ...

s such as

arithmetic logic unit In computing, an arithmetic logic unit (ALU) is a Combinational logic, combinational digital circuit that performs arithmetic and bitwise operations on integer binary numbers. This is in contrast to a floating-point unit (FPU), which operates on ...

s or multipliers that perform data processing operations,

register Register or registration may refer to: Arts entertainment, and media Music * Register (music), the relative "height" or range of a note, melody, part, instrument, etc. * ''Register'', a 2017 album by Travis Miller * Registration (organ), the ...

s, and

buses A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...

. Along with the

control unit The control unit (CU) is a component of a computer's central processing unit (CPU) that directs the operation of the processor. A CU typically uses a binary decoder to convert coded instructions into timing and control signals that direct the ope ...

it composes the central processing unit (CPU). A larger datapath can be made by joining more than one datapaths using multiplexers. A data path is the ALU, the set of registers, and the CPU's internal bus(es) that allow data to flow between them. Single bus organization

The simplest design for a CPU uses one common internal bus. Efficient addition requires a slightly more complicated three-internal-bus structure. Many relatively simple CPUs have a 2-read, 1-write

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- ...

connected to the 2 inputs and 1 output of the ALU. During the late 1990s, there was growing research in the area of reconfigurable datapaths—datapaths that may be re-purposed at run-time using programmable fabric—as such designs may allow for more efficient processing as well as substantial power savings.

Finite state machine with datapath

A finite-state machine with datapath (FSMD) is a mathematical abstraction which combines a

finite-state machine A finite-state machine (FSM) or finite-state automaton (FSA, plural: ''automata''), finite automaton, or simply a state machine, is a mathematical model of computation. It is an abstract machine that can be in exactly one of a finite number o ...

, which controls the

program flow In computer science, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative program are executed or evaluated. The emphasis on explicit control flow distinguishes an ''imper ...

, with a datapath. It can be used to design

digital logic A logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more Binary number, binary inputs that produces a single binary output. Depending on the context, the term may refer to an id ...

computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer program ...

s. FSMDs are essentially sequential programs in which statements have been scheduled into states, thus resulting in more complex state diagrams. Here, a program is converted into a complex state diagram in which states and arcs may include

arithmetic expression In mathematics, an expression or mathematical expression is a finite combination of symbols that is well-formed according to rules that depend on the context. Mathematical symbols can designate numbers ( constants), variables, operations, f ...

s, and those expressions may use external inputs and outputs as well as variables. The FSMD level of abstraction is often referred to as the

register-transfer level In digital circuit design, register-transfer level (RTL) is a design abstraction which models a synchronous digital circuit in terms of the flow of digital signals (data) between hardware registers, and the logical operations performed on those ...

. FSMs do not use variables or arithmetic operations/conditions, thus FSMDs are more powerful than FSMs. An FSMD is equivalent to a

Turing machine A Turing machine is a mathematical model of computation describing an abstract machine that manipulates symbols on a strip of tape according to a table of rules. Despite the model's simplicity, it is capable of implementing any computer algori ...

in expressiveness.

References

Central processing unit Digital electronics {{CPU technologies