Embedded System Terminology - D
| Daisy Chain - A type of digital circuit in which components are connected in series (in a “chain-like” structure), and where signals pass through each of the components down through the entire chain. Components at the top of the chain essentially can impact (slow down, block, etc.) a signal for being received by components further down in the chain. |
| Datagram - What the networking data received and processed by the networking layer of the OSI model or corresponding layer in other networking models (the Internet layer in the TCP/IP model) is called. |
| Data Bus - A set of electrical signals connected to the processor and all of the memory and peripheral devices with which it communicates for the purpose of transferring data between them. |
| Data Acquisition System - System which acquires data, generally by digitizing analog channels and storing the data in digital form. These systems can be standalone or coupled to a computer and can acquire multiple channels of data. |
| Data Communications Equipment (DCE) - The device that the DTE wants to serially communicate with, such as an I/O device connected to the embedded board. |
| Data Terminal Equipment (DTE) - The initiator of a serial communication, such as a PC or embedded board. |
| Deadline - In a real-time system, the time at which a particular set of computations or data transfers must be completed. There are typically consequences associated with missing a deadline. If the deadline absolutely, positively must be met every time or else, it is called a hard deadline. Hard deadlines have dire consequences when missed. Other deadlines are said to be soft deadlines. |
| Deadlock - An undesired result related to the use of an operating system, in which a set of tasks are blocked, awaiting an event to unblock that is controlled by one of the tasks in the blocked set. |
| Debounce - Electrical contacts in mechanical pushbutton switches often make and break contact several times when the button is first pushed. A debouncing circuit removes the resulting ripple signal, and provides a clean transition at its output. |
| Debugger - A software tool used to test for, track down, and fix bugs. |
| Debug Monitor - A piece of embedded software that has been designed specifically for use as a debugging tool. |
| Decimal - A base-10 number system, meaning there are 10 symbols (0-9), used in a variety of combinations to represent data. |
| Decoder - A circuit or software that translates encoded data into the original format of the data. |
| Delay Line - An electrical component that delays the transmission of a signal. |
| Demodulation - Extracting data from a signal that was modified upon transmission to include a carrier signal and the added transmitted data signal. |
| Demultiplexor (Demux) - A circuit which connects one input to more than one output, where the value of the input determines which output is selected. |
| Device Driver - Software that directly interfaces with and controls hardware. |
| Device Programmer - A tool for programming EPROMs, PLDs, nonvolatile memories, and other electrically programmable devices. |
| Dhrystone - A benchmarking application which simulates generic systems programming applications on processors, used to derive the MIPS (Millions of Instructions per Second) value of a processor. |
| Die - The portion of an integrated circuit that is made of silicon, that can either be enclosed in some type of packaging or connected directly to a board. |
| Dielectric - An insulative layer of material found in some electrical components, such as capacitors. |
| Diode - A two-terminal semiconductor device that allows current flow in one direction, and blocks current which flows in the opposite direction. |
| Differentiator - A circuit that calculates a mathematical (calculus) derivative output based on a given input. |
| Digital - A signal that is expressed as some combination of one of two states, a “0” or “1”. |
| Digital Filter - A filter that's implemented digitally. A digital filter accepts digital inputs (typically samples read from an ADC) and produces digital outputs. The data is processed in firmware running on a digital signal processor. |
| Digital-to-Analog Converter (D/A Converter) - A hardware device that takes a set of bits, typically from a processor, as input and produces an analog signal proportional to the digital input as output. |
| Digital Signal Processor (DSP) - A type of processor that implements a datapath ISA, and is typically used for repeatedly performing fixed computations on different sets of data. |
| Digital Subscriber Line (DSL) - A broadband networking protocol that allows for the direct digital transmission of data over twisted pair wired (POTS) mediums. |
| Digital-to-Analog Converter (DAC) - A device that converts digital signals to analog signals. |
| Direct Current (DC) - Current that flows constantly in the same direction in a circuit. DC current is defined by two variables: polarity (the direction of the circuit) and magnitude (the amount of current). |
| Direct Memory Access (DMA) - A scheme in which data is exchanged between I/O and memory components on a board with minimal interference from and use of the master processor. |
| Disassembler - Software that reverse-compiles the code, meaning machine language is translated into assembly language. |
| Domain Name Service (DNS) - An OSI model session layer networking protocol that converts domain names into internet (network layer) addresses. |
| Down Counter - A counter that counts down, from its maximum value toward zero. |
| Dual Inline Memory Module (DIMM) - A type of packaging in which memory ICs can come in, specifically a mini-module (PCB) that can hold several ICs. A DIMM has protruding pins from 1 side (both on the front and back) of the module that connect into a main embedded motherboard, and where opposing pins (on the front and back of the DIMM) are each independent contacts. |
| Dual Inline Package (DIP) - A type of packaging that encloses a memory IC, made up of ceramic or plastic material, with pins protruding from two opposing sides of the package. |
| Dual Port Random Access Memory (DPRAM) - RAM that can connect to two buses allowing for two different components to access this memory simultaneously. |
| Dynamic Host Configuration Protocol (DHCP) - A networking layer networking protocol that provides a framework for passing configuration information to hosts on a TCP/IP-based network. |
| Dynamic Random Access Memory (DRAM) - RAM whose memory cells are circuits with capacitors that hold a charge in place (the charges or lack thereof reflecting the data). |
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Related topics:
Embedded System Architecture | Embedded Hardware Architecture | Embedded Software Architecture | Embedded Software Definition | Embedded System Acronyms | Embedded System Symbols
List of topics: Embedded System
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