Merge pull request #2 from AllysonProlisko/AllysonProlisko-patch-2

Update Glossary

Author: AllysonProlisko

docs/Glossary

@@ -1,42 +1,194 @@
 Glossary
 ========
 
-+-----------------------+----------------------------------------------+
-| .. rubric:: Term      | .. rubric:: Definition                       |
-|    :name: term        |    :name: definition                         |
-+=======================+==============================================+
-+-----------------------+----------------------------------------------+
-
-+-------------------+--------------------------------------------------+
-| Amaranth          | An open-source toolchain for developing hardware |
-|                   | based on synchronous digital logic using the     |
-|                   | Python programming language                      |
-+===================+==================================================+
-| ASIC              | Application-specific integrated circuit          |
-+-------------------+--------------------------------------------------+
-| Domain            | A group of logic elements                        |
-+-------------------+--------------------------------------------------+
-| DUT               | Device under test                                |
-+-------------------+--------------------------------------------------+
-| Finite state      | A mathematical model for a system that has a     |
-| machine           | limited number of conditional states of being    |
-+-------------------+--------------------------------------------------+
-| FPGA              | Field Programmable Gate Array — a design,        |
-|                   | blueprint, template                              |
-+-------------------+--------------------------------------------------+
-| HDL               | Hardware definition language                     |
-+-------------------+--------------------------------------------------+
-| IC                | Integrated circuit                               |
-+-------------------+--------------------------------------------------+
-| Logic gate        | A basic circuit with at least one — usually more |
-|                   | — inputs and one output                          |
-+-------------------+--------------------------------------------------+
-| LUT               | Look up table                                    |
-+-------------------+--------------------------------------------------+
-| MCU               | Microcontroller unit                             |
-+-------------------+--------------------------------------------------+
-| Propagation delay | The time it takes for a signal to move from      |
-|                   | source to destination                            |
-+-------------------+--------------------------------------------------+
-| RTL               | Register transfer language                       |
-+-------------------+--------------------------------------------------+
+**Amaranth**
+| An open-source toolchain that uses the Python programming language.
+| Amaranth makes developing hardware definitions, based on synchronous
+  digital logic, more intuitive by using the popular Python programming
+  language. The toolchain consists of the Amaranth language, the
+  standard library, the simulator, and the build system, covering all
+  steps of a typical FPGA development workflow.
+
+**ASIC (Application-specific integrated circuit)**
+| A non-standard integrated circuit chip made for a specific task or
+  product.
+| The term *application* refers to the function the circuit will
+  perform, not to a software application.
+| ASICs can be configured to be more power efficient and have better
+  performance than an off-the-shelf general purpose integrated circuit.
+  However, unlike FPGAs, ASICs cannot be reprogrammed and are expensive
+  to produce so design and testing are critical to the success of ASIC
+  development.
+| Rather than designing and building them from the ground up, ASICs can
+  be created by interconnecting functional components from cell
+  libraries. The resulting system can then be verified via simulation.
+
+**CLB (Configurable logic block)**
+| The basic repeating logic block on an FPGA, the purpose of CLBs is to
+  implement combinational and sequential logic on an FPGA.
+| Each FPGA contains many logic blocks that are surrounded by a system
+  of programmable interconnects (I/O blocks), called a fabric, that
+  routes signals between the CLBs.
+| The three essential components of a logic block are flip-flops, LUTs,
+  and multiplexers.
+
+**Clock signal**
+| An electronic logic signal that oscillates between a high and a low
+  state at a constant frequency, used to synchronise the actions of
+  digital circuits
+| The clock signal enters the FPGA system through a single physical
+  connecting pin and is responsible for the speed at which an FPGA can
+  run and process data.
+| A wave at a particular frequency is distributed across the FPGA to
+  produce a synchronised response from all the flip-flops in the design.
+  Performance of the system will be affected if the flip-flops do not
+  all receive the clock signal at the same time. It’s possible to use
+  more than one clock in an FPGA design but it is complicated and
+  requires a degree of skill in circuit design.
+
+**DUT (Device under test)**
+| A manufactured device that is being tested for performance and
+  proficiency.
+| The device fails testing as soon the first out-of-tolerance value is
+  identified. The aim is to ensure damaged devices don’t enter the
+  market.
+
+**Finite state machine**
+| A mathematical model describing a system with a limited number of
+  conditional states of being.
+| A finite state machine reads a series of inputs. For each input, it
+  will transition to a different state. Each state specifies which state
+  to transition to next, for the given input. When the processing is
+  complete, a ‘then’ action is taken. The abstract machine can process
+  only one state at a time.
+| This approach enables engineers to study and test each input and
+  output scenario.
+
+**Flip-flop**
+| The basic memory element for storing a single bit of information.
+| An edge-triggered device, it reacts to the edge of a pulse. Flip-flops
+  synchronise logic and save logical states between clock cycles within
+  an FPGA circuit. On every rising or falling clock edge, a flip-flop
+  latches the 1 or 0 (TRUE or FALSE) value on its input and holds that
+  value constant until the next clock edge.
+
+**FPGA (Field Programmable Gate Array)**
+| A reconfigurable integrated circuit containing internal hardware
+  blocks with user-programmable interconnects to create a customised
+  application.
+| The device’s physical attributes are programmed using a hardware
+  definition language. I /O blocks interface between the FPGA and
+  external devices.
+| FPGAs combine speed, programmability, and flexibility: FPGAs don't
+  jump between memory and programming in the way ASICSs and CPUs do, so
+  storing and retrieving data is more efficient. In addition, they can
+  process very large volumes of data by duplicating circuits and running
+  them in parallel.
+
+**Hardware register**
+| Circuits, typically composed of flip flops, often with characteristics
+  similar to memory and having additional hardware-related functions.
+| Hardware registers are used in the interface between software and
+  peripherals.
+
+**HDL (Hardware description language)**
+| Hardware description languages describe the structure, behaviour, and
+  timing of electronic circuits and digital logic circuits.
+| HDLs describe behavioural, register transfer, gate, and switch-level
+  logic. Behavioural level logic enables the sequential execution of
+  instructions; and register transfer logic enables the transfer of data
+  between registers. These actions are driven by an explicit clock and
+  gate level logic that defines the individual gate level logic. HDLs
+  can also be used to simulate a circuit and verify its response.
+
+**IC (Integrated circuit)**
+| An integrated circuit is a computer chip that has an electronic
+  circuit embedded in it.
+| The circuit is a small wafer, usually made of silicon, that can hold
+  anywhere from hundreds to millions of transistors, resistors, and
+  capacitors. These components can perform calculations and store data
+  using either digital or analog technology.
+| Digital ICs use logic gates that work only with values of 1s and 0s. A
+  low signal sent to a component on a digital IC will result in a value
+  of 0, while a high signal creates a value of 1.
+
+**Logic gate**
+| An elementary building block of integrated circuits, logic gates
+  perform logical operations on binary inputs and outputs.
+| Based on a Boolean function that computes TRUE or FALSE, each output
+  is based on the input or combination of inputs supplied to it.
+| **LUT (Look up table)**
+
+| An elementary building block of integrated circuits, a LUT is a truth
+  table that defines how combinatorial logic behaves: the output for
+  every combination of inputs.
+| The computation is very fast because the function requires only a
+  single memory lookup regardless of the complexity of the function.
+
+**MCU (Microcontroller unit)**
+| A compact integrated circuit designed to govern a specific operation
+  in an embedded system.
+| An MCU typically comprises a processor unit, memory modules,
+  communication interfaces, and peripherals.
+
+**Multiplexer**
+| A combinational logic circuit designed to switch one of several inputs
+  through to a single common output by the application of a control
+  signal.
+| A multiplexer makes it possible for several input signals to share one
+  device or resource instead of having one device per input signal. They
+  use high speed logic gates to switch digital or binary data through to
+  a single output.
+
+**Propagation delay**
+| The time required to change the output from one logic state to another
+  logic state after input is applied.
+| In simplified terms, the time it takes for a signal to move from
+  source to destination. The timing begins when the input to a logic
+  gate becomes stable and valid to change and ends when the output of
+  that logic gate is stable and valid to change.
+| The propagation delay of a complete circuit is calculated by
+  identifying the longest path of propagation delay from input to output
+  and adding each propagation delay along the path.
+
+**RTL (Register transfer level)**
+| RTL is used to create high-level representations of a circuit, from
+  which lower-level representations and wiring can be derived.
+| It models a synchronous digital circuit in terms of the flow of
+  digital signals between hardware registers, and the logical operations
+  performed on those signals.
+
+**Simulation**
+| A process in which a model of an electronic circuit is replicated and
+  analysed to verify its functionality.
+| Simulation is an invaluable tool for ensuring a circuit works the way
+  it was intended to by checking accuracy, capacity, and performance. It
+  also enables designers to rapidly iterate designs and test them to
+  find the optimal configuration.
+
+**SoC (System on Chip)**
+| An integrated circuit, containing all the circuitry and components an
+  electronic system requires.
+| In contrast to a traditional computer system that is made up of many
+  distinct components, an SoC integrates the required resources — CPU,
+  memory interfaces, I/O devices, I/O interfaces, secondary storage
+  interfaces — into a single chip. SoCs are typically built around a
+  microprocessor, microcontroller, or specialised integrated circuit.
+  This increases performance, reduces power consumption, and requires a
+  smaller semiconductor die area.
+
+**Wave form**
+| A visual representation of the variation of a voltage or current over
+  time.
+| Periodic waveforms vary at a given frequency, for example, the voltage
+  or current of a signal is amplified or reduced to provide a clock
+  signal for an FPGA.
+| Waveforms have three main characteristics: period, the length of time
+  the waveform takes to repeat; frequency, the number of times the
+  waveform repeats within a one second time period; and amplitude, the
+  magnitude or intensity of the signal waveform measured in volts or
+  amps.
+| The waveform of an electrical signal can be visualised in an
+  oscilloscope or similar instrument that can capture and plot the
+  variations in the signal. The square waveform is commonly used to
+  represent digital information.