Embedded Systems

RTOS

(RealTime Operating System) An operating system designed for use in a realtime computer system

(RTOs) (RealTime Operations) Procedures within an organization that enable information to be distributed to all parties in realtime. It implies that day-to-day activities are integrated with existing information systems so that vital up-to-date information is always available to management, employees and the public as required.

Vx WORKS

A popular realtime operating system for embedded systems from Wind River, Alameda, CA (www.windriver.com). It is used to control a wide variety of products, including network and telecom devices, test and measurement equipment, computer peripherals and consumer products. It is also used in the automotive and aerospace industries for engine control and avionics. Available for a large number of CPU types, applications are created in Wind River's Tornado development environment.

FIRMWARE

A category of memory chips that hold their content without electrical power. Firmware includes flash, ROM, PROM, EPROM and EEPROM technologies. When holding program instructions, firmware can be thought of as "hard software."

BIOS

Basic Input Output System) An essential set of routines stored in a chip that provides an interface between the operating system and the hardware in a PC. The BIOS supports all peripheral technologies including drives as well as internal services such as the realtime clock (time and date). BIOS settings are maintained in a tiny battery-backed memory

QNX

A multiuser, multitasking, realtime operating system for PCs from QNX Software Systems, Ltd., Ottawa, Ontario (www.qnx.com), that is noted for its low-memory requirement and rapid response. Similar to Unix, it has been in use since the early 1980s

MPEG

Moving Pictures Experts Group) An ISO/ITU standard for compressing digital video. Pronounced "em-peg," it is the universal standard for digital terrestrial, cable and satellite TV, DVDs and digital video recorders (DVRs).

MPEG uses lossy compression within each frame similar to JPEG, which means pixels from the original images are permanently discarded. It also uses interframe coding, which further compresses the data by encoding only the differences between periodic frames. MPEG performs the actual compression using the discrete cosine transform (DCT) method.

MPEG is an asymmetrical system. It takes longer to compress the video than it does to decompress it in the DVD player, PC, set-top box or digital TV set. As a result, in the early days, compression was perfomed only in the studio. As chips advanced and became less costly, they enabled digital video recorders, such as Tivos, to convert analog TV to MPEG and record it on disk in realtime.

JPEG

(Joint Photographic Experts Group) An ISO/ITU standard for compressing still images. Pronounced "jay-peg," the JPEG format is very popular due to its variable compression range. JPEGs are saved on a sliding resolution scale based on the quality desired. For example, an image can be saved in high quality for photo printing, in medium quality for the Web and in low quality for attaching to e-mails, the latter providing the smallest file size for fastest transmission over dial-up connections.

SET TOP BOX

The cable TV box that "sits on top" of the TV set. It descrambles the premium channels and provides a tuner for the higher cable numbers that very old TVs did not support. Originally only analog, digital set-top boxes have become widely used for digital services that offer an on-screen program guide. Digital set-top boxes that provide high-definition TV (HDTV) are the latest version.

With satellite TV, a device similar to the set-top box decodes signals for viewing. However, although some call it a "satellite set-top box," it is officially known as a "satellite TV receiver."

DVB

(Digital Video Broadcasting) An international digital television (DTV) standard that is the European and Far Eastern counterpart of the North American ATSC standard. Administered by the DVB Project within the European Telecommunications Standards Institute (ETSI), DVB uses MPEG-2 for video compression and MPEG-2 and Dolby Digital for audio.

MICROPROCESSORS

A central processing unit (CPU) contained within a single chip. Today, all computer CPUs are microprocessors. The term originated in the 1970s when CPUs up until that time were all comprised of several chips. Thus, when the entire CPU (processor) was miniaturized onto a single chip, the term "micro" processor was coined. Since the turn of the century, the semiconductor manufacturing process has become so sophisticated that not only one, but two or more CPUs, are built on a single chip

MICROCONTROLLER

A single chip that contains the processor (the CPU), non-volatile memory for the program (ROM or flash), volatile memory for input and output (RAM), a clock and an I/O control unit. Also called a "computer on a chip," billions of microcontroller units (MCUs) are embedded each year in a myriad of products from toys to appliances to automobiles. For example, a single vehicle can use 70 or more microcontrollers.

Microcontrollers come in all sizes and architectures, with the smaller, commodity chips costing as little as 50 cents in quantities of 10,000.

ADA

A high-level programming language developed by the U.S. Department of Defense along with the European Economic Community and many other organizations. It was designed for embedded applications and process control but is also used for logistics applications. Ada is a Pascal-based language that is very comprehensive.

Ada was named after Augusta Ada Byron (1815-1852), Countess of Lovelace and daughter of the poet Lord Byron and mathematician Annabella Milbanke Byron. Ada also became a mathematician and was the colleague of Charles Babbage, who was developing his Analytical Engine. Some of her programming notes for the machine have survived, giving her the distinction of being the first documented programmer in the world