Wide Area Augmentation System. A system of North American ground stations that monitor GPS signals, adjust for clock or orbit drift and signal delays, and generate correction messages to be transmitted by geostationary satellites. A GPS receiver in North America that is WAAS-enabled can receive these messages and use them to improve location accuracy (to within about 3m instead of the typical 15m). Europe is deploying a similar system called Egnos.
Wireless Avionics Intra-Communications. Pronounced “wake”. Any system that provides wireless communication between internal systems of an aircraft. It dispenses with the cost and weight of running cables, but raises safety and security issues.
Wireless Application Protocol. A standard for developing apps for wireless Internet devices. It uses WML and WSP, plus other protocols, and allows graphical data to be received, displayed, and manipulated on the screen of a mobile phone.
The practice of scanning an area for wireless LANs with weak or no security, typically from a moving vehicle, and typically with criminal intent. Descended from the older wardialing – using a dial-up modem to hunt for Internet-connected computers with no security. The 1983 movie WarGames, which featured wardialing, might have been the inspiration for the term.
A newer technique, dubbed warshipping, is to send a package to the target organization that contains a small, low-power, single-board computer with a mobile-phone modem and Wi-Fi capability. The attackers control it via the mobile-phone connection, and use its Wi-Fi to attack the organization’s network until someone in the mail room opens the package and, with luck, knows to turn it off.
WAVEform Audio Format. A 1990 IBM/Microsoft format for audio files, using the .wav extension. A WAV file consists of a fixed-length header and a body, and can be compressed or not. Later formats, starting with MP3, yield equivalent sound quality with much smaller files.
A conduit, most often a metal tube, for carrying microwave-frequency EM waves, especially to and from antennas. It can operate with lower transmission losses than a cable. Because its width is proportional to the wavelength it’s optimized for, this type of waveguide is not practical outside the microwave band.
There are solid dielectric waveguides. In fact, that’s what a fiber-optic cable is. Researchers have demonstrated the use of laser pulses to create temporary virtual waveguides in air.
A brief burst of RF energy that exhibits some oscillation in time. Wavelet modulation has emerging uses for increasing bandwidth efficiency. A wavelet has two variables: translation and scale. A single wavelet equation generates an entire family of orthogonal wavelets for use in modulation by translating (time-shifting) and dilating (time-scaling) itself.
Web Content Accessibility Guidelines. A set of W3C guidelines, adopted as an ISO standard, for designing Web sites to be accessible to people who have disabilities, or are using less capable technologies such as small-screen devices.
Watchdog Timer. A timer with the capability to reset a microprocessor or microcontroller, freeing it from infinite loops and other unrecoverable states. Common in embedded devices. It can be a software counter, or part of processor hardware, or an external device. If the WDT is enabled, processor code must constantly reset it to keep it from going off, a process called feeding the dog.
Short for the World Wide Web. Capitalize it. Web sites following the largely static template of the original WWW as debuted in the 1990s and exemplified by this site are sometimes described as being part of Web 1.0, in contrast to what came later.
Generally understood as shorthand for the loose online community of corporations and organizations that promote and deal in cryptocurrencies and NFTs. As covered at https://web3isgoinggreat.com/, it can also mean a hoped-for Web of the future based on blockchains, elimination of censorship, and egalitarian ideals.
Abbreviated as wasm. A standard format for Web page design created in 2015, supported by the new Rust programming language, and being added to JavaScript. Rather than sending client-side scripts that the client browser must interpret, it sends pre-compiled low-level code. This means faster page load times, and also faster performance on the client side. The code can even include a virtual machine that runs in the browser.
Web-based Graphics Library. A library and API for providing interactive 3D Web graphics with JavaScript. It’s based on OpenGL. Modern browsers support it, or partially support it.
Windows Experience Index. A set of five hardware performance scores reported by the Windows System Assessment Tool (WinSAT) that comes with Windows Vista and Windows 7. Unless the user prevents it, the OS adjusts its default system settings based on these scores.
Wired Equivalent Privacy. An encryption scheme used by wireless networks, particularly 802.11b. The name reflects the intent that defeating it be roughly as difficult as tapping a wired LAN. This turns out not to be the case. The original WEP uses 40-bit encryption. WEP 2.0 uses 128-bit encryption. Both have been broken by sophisticated attacks, and tools to simplify such attacks are available on the Internet. For that reason, Wi-Fi implementations now offer WPA.
Web Hypertext Application Technology Working Group. A Web technologies group created by networking industry figures frustrated with the W3C. It started the development of HTML 5, which, in contrast to the W3C, it envisions as a living standard that will continuously add and change but not remove functionality.
A TCP/IP protocol to query Internet servers for ownership and other information on a domain name or IP address. Many Internet sites offer free Whois lookup. However, don’t check availability of a domain with the service provided by a domain name registrar company, as they have a conflict of interest; go through a non-registrar such as IANA or ICANN. Also, if setting up a Web site, use one company for domain name registration and another for hosting the site.
Whois conflicts with the European Union’s 2018 GDPR privacy law. ICANN and the EU have not resolved the issue as of 2020.
(Due 2016/2017) A high-speed, low-power, JEDEC-approved memory bus and configuration created by Samsung, primarily for SoC-based mobile devices. Like HBM and HMC, it uses 3D stacked structures to minimize interconnect distance.
Wireless Fidelity. Riffing on the term hi-fi, this is a popular name for most (not all) of the 802.11 wireless network protocols. Specifically, the names Wi-Fi 1 through Wi-Fi 7 are applied to, in order, the original standard 802.11 and its descendants 802.11b, 802.11g, 802.11n, 802.11ac, 802.11ax, and 802.11be.
An obsolete term for a spinning magnetic hard disk drive (HDD). Its ancestor, the 1973 IBM model 3340 hard drive, had two spindles, one permanent and one removable. Each held 30 MB, so the drive was referred to as a “30-30”, which reminded people of the Winchester Model 94 lever-action rifle, popularly known as the .30-30.
An approach to FIR digital filtering: producing frequency-bounded (i.e. filtered) samples of a time-domain digital signal x[n] by repeatedly multiplying it with a finite N-length sequence w[n], known as a windowing function. (Remember, a multiplication in the time domain is a convolution in the frequency domain.)
The rectangular windowing function (w[n] = 1 for {0 ≤ n < N}, and w[n] = 0 for all other values of n) has modest rolloff and causes sharp discontinuities in the samples, which show up in the FFT as high stopband ripple. This makes it unsuited for filtering continuous signals. Therefore, the rectangular window is normally scaled by multiplication with some other window function that decays to 0 at the boundaries. The basic types are:
triangular (Bartlett) – Named for English mathematician Maurice S. Bartlett (1910-2002), this is a simple triangular function.
raised cosine – Any of the form w[n] = A – B cos [2πn/(N–1)] + C cos [4πn/(N–1)], for a set of constants A, B, and C. Common in audio processing.
Hamming – Named for American mathematician Richard W. Hamming (1915-1998). A type of raised cosine, w[n] = 0.54 – 0.46 cos [2πn/(N–1)].
Hann – Named for Austrian meteorologist and physicist Julius Ferdinand von Hann (1839-1921). A type of raised cosine, w[n] = 0.5 – 0.5 cos [2πn/(N–1)]. Often called the Hanning window, apparently for symmetry with “Hamming”.
Blackman – Named for American mathematician Ralph B. Blackman (1904-1990). A type of raised cosine, w[n] = 0.42 – 0.5 cos [2πn/(N–1)] + 0.4 cos [4πn/(N–1)].
More complex windowing function types include Kaiser, Bessel, Butterworth, Chebyshev I & II, elliptic (equiripple), etc. Each has its strengths and weaknesses.
A large family of PC operating systems from Microsoft. Early versions kept configuration and default data about Windows applications and user accounts in initialization (*.ini) files. Newer versions store this data in the Windows registry, a hierarchical system database accessible via the REGEDIT.EXE program. Also, see VM. The Windows family members – in chronological rather than alphabetical order – are listed below.
Windows #.# – Versions 1.0 (1985), 3.0 (1990), and 3.1 (1992) were 16-bit OSes running on top of MS DOS. Windows 3.11 and 3.11 for Workgroups are 16/32-bit.
Windows NT – (1993) New Technology. This 32-bit OS, the beginning of Microsoft’s inroad on the network and database server market, comes in the NT Workstation, NT Server, and NT Enterprise Server flavors. Besides the x86, NT supports Alpha, MIPS, and PowerPC processors. The NT kernel runs in protected memory and tightly controls access to hardware, which makes it a lousy games platform. Applications that directly access hardware will not run on NT. Introduced the NTFS file system and Win32 API.
Windows 95 – (1995) A 16/32-bit OS for the home and small business market. It introduced DirectX, an API that developers were supposed to program to instead of to the underlying hardware. However, it still permitted real-mode applications to access hardware directly. The official version numbers are 4.00.950 (the first release), 4.00.950a (SP1), 4.00.950B (OSR2, which introduced the FAT32 file system), 4.00.950B + USB (OSR2.1), and 4.00.950C (OSR2.5).
Windows CE – (1996) Consumer Electronics, maybe. A compact, real-time 32-bit version of Windows. Variants exist for use in PDAs, cell phones, embedded devices, and even cars.
Windows 98 – (1998) The successor to Windows 95 – really just an upgrade (version 4.10.1998), still 16/32-bit. It fully integrated the FAT32 file system that was introduced in Windows 95 version 4.00.950B.
Windows SE – Second Edition. A revision of Windows 98 (version 4.10.2222).
Windows 2000 – (2000) The more stable successor to Windows NT, although it supports the FAT32 file system as well as NTFS. Unlike NT, it doesn’t run on non-x86 processors. There are four varieties for increasingly demanding roles: Professional (to supplant NT Workstation), Server, Advanced Server, and Datacenter Server. Then there’s Server 64-Bit. Windows 2000 Professional requires about 75 MB of RAM just for OS functions.
Windows ME – (2000) Millennium Edition. An updated version of Windows 98 (version 4.90.3000), intended primarily for the home user who doesn’t need DOS support for older devices.
Windows XP – (2001) eXPerience. Also called Windows 5.1. Windows XP Home is meant for home use, and Windows XP Pro for the business market. It’s built on the Windows NT hybrid kernel, and can use the FAT16, FAT32, and NTFS file systems, although FAT can’t format hard drives larger than 32 GB or handle files exceeding 4 GB. XP is more stable than older Windows, but takes more room: it requires about 1 GB of drive space, creates a minimum 300 MB swap file, and uses 80-90 MB of RAM just for OS functions. It shouldn’t be attempted with less than 256 MB of RAM and a 300 MHz processor. XP has native support for DVD, CD-RW, ATA100, UPnP, IEEE 1394 (FireWire), and 802.11b. XP Pro supports dual CPUs, dual monitors, and 64-bit code.
Microsoft discontinued security updates for XP as of April 2014, and for Windows 7 and Windows Server 2008 in January 2020. For the latter two, an extended security update (ESU) service is available until 2023 or 2024.
Windows 2003 – More powerful versions of XP: Server, Advanced Server, and DataCenter.
Windows Vista – (January 2007) Built with network security and multi-core processors in mind. It comes in 32- and 64-bit, which probably should have minimum 1 GB and 2 GB RAM, respectively, and has Home Basic, Home Premium, Business, and Ultimate editions. Its file system – NTFS plus the new Transactional File System (TxF) – works like a browser for the hard drive rather than presenting a hierarchical file structure.
Windows Server 2008 – A.k.a. Longhorn, a server OS that started as an upgrade of XP.
Windows 7 – (Fall 2009) Like Vista, it comes in 32- and 64-bit. The editions are called Home Premium, Ultimate, and Professional, and are further divided into Upgrade (install over older version of Windows) and OEM (new system install).
Windows 8 – (October 2012) 32- or 64-bit. A touchscreen-capable x86 OS designed with smartphones and tablets in mind, but intended for desktops as well. In addition to the basic Windows 8 release, there are Windows 8 Pro and Windows 8 Enterprise versions. Installations use either the old NTFS or the new ReFS file system. Microsoft’s Surface tablet/notebook PC will run Windows 8 (Pro), but its ARM-based Surface RT does not. Windows 8 does not require a TPM on the hardware, unlike Windows RT, but it will automatically activate the TPM on a system that has one installed.
Windows 8.1 (October 2013) addresses some of the complaints users had about the initial release’s changes to the interface, but not the missing start-button menu, which accessed installed programs in all previous versions of Windows. Independent developers have created applications that restore this and other lost capabilities.
Microsoft will discontinue security updates for Windows 8 as of 10 Jan 2023.
Windows RT – (October 2012) Windows RunTime, unofficially. 32-bit. It presents the same user interface as Windows 8, but is very different under the hood, because it’s for ARM-based tablet PCs rather than x86 systems. This means it won’t run software created for any other type of Windows. It’s available only pre-installed, and only on hardware that uses UEFI secure boot implemented by a TPM to authenticate the OS. Microsoft co-released a touchscreen tablet/notebook PC for it called Surface RT.
Windows 10 – (2015) 32- or 64-bit. Meant to improve on the desktop experience of the touchscreen-oriented Windows 8. (There is no Windows 9.) Once again, the desktop versions are Home, Enterprise, and Professional, and there are the Mobile and Mobile Enterprise versions for tablets and smartphones. There are also Windows 10 IoT for computing devices such as Arduino and Raspberry Pi, and Windows 10 Education for students. Secure Boot (see Trusted Computing) is optional on desktop versions, mandatory on mobile versions.
To install Windows 10 with a traditional local account rather than one that forces the user to a Microsoft login, it’s become necessary as of 2019 to disconnect the PC from the Internet during installation.
Windows 11 – (2021) 64-bit, available as an update of Windows 10 as well as an OEM install. It comes in two flavors, Windows 11 Home and Windows 11 Pro, and has changes to the interface, many new features, and some improvements to efficiency. It’s possible to install Windows 11 with a local account instead of a Microsoft account, but the installer makes it difficult (see dark pattern). Windows 11 also attempts to enforce the use of Secure Boot. Again, there are ways around it.
Executable software (.exe) that runs in the background under Microsoft Windows and responds to requests from other software, comparable to the Unix daemon and sort of comparable to the MS-DOS TSR. Windows assigns a status to each installed service: automatic (run at startup), manual (run when started by a user action), or disabled (don’t run). Software installers always want their service to run at startup, but the user can change the setting. Windows Task Manager displays a list of all the services on the system, running or not.
Windows Sockets. Based on the sockets API of BSD (Berkeley) Unix, this is a Windows API created by non-Microsoft programmers that accesses the network via function calls to the TCP/IP protocol stack managed by the kernel. In simpler language: It’s a program that provides a standard way for other Windows programs to use the network. Almost any application conforming to Winsock can run over the stack. Winsock doesn’t address all TCP/IP functions, however.
The Berkeley API has standard sockets, which access the network through the kernel’s TCP/IP, and also raw sockets, which allow an application to handle its own packet formatting and send packets directly to other applications. Winsock 1 (1992), which is a single 16-bit or, later, 32-bit DLL, has only standard sockets. The WOSA-compliant Winsock 2 (1996), a hierarchical set of DLL files used for Windows XP and all later versions of Windows, has raw sockets as well.
Wafer-Level Packaging. Also called Wafer-Level Chip-Scale Packaging (WLCSP). An advance on CSP, putting an entire IC wafer in a surface-mount package rather than packaging IC chips cut from a wafer. The package’s board surface is required to be no larger than the bare wafer.
Windows Media Audio. Microsoft proprietary format (released in 2000) for lossy compression of audio files, using the .wma filename extension. It has strong copyright protection. See ASF.
Wireless Markup Language. Scaled down from HTML to present WWW content in the cramped environment of mobile hand-held devices. A micro-browser in the device reads and interprets the WML. See WAP.
Wireless Medical Telemetry Service. A 14 MHz portion of the spectrum in three bands: 608-614 MHz, 1395-1400 MHz, and 1429-1432 MHz. Allocated in 2000, it’s smaller than ISM, but free from other, non-medical uses, supposedly making it safer for critical applications.
Windows Media Video. Microsoft proprietary format for audio-video files, using the .wmv extension. Originally based on MPEG-4, but not compatible, of course. There’s also WMV HD (Windows Media High Definition Video). See ASF.
Windows Open System Architecture. A Microsoft idea to hide Windows programming complexities from users and developers alike. It defines a common set of APIs (TAPI, MAPI, et al) that interconnect different applications. Developers write to these APIs instead of to the Windows environment.
Wi-Fi Protected Access. Encryption systems for Wi-Fi (802.11x) networks, introduced by the Wi-Fi Alliance in response to vulnerabilities in WEP. WPA uses the Temporal Key Integrity Protocol (TKIP), based on RC4 encryption with a 128-bit key. The newer WPA2 also uses a version of AES.
WPA3, released in 2018, comes in Personal and Enterprise flavors. It provides a separate 128-bit or 192-bit encryption stream for each connected device to prevent eavesdropping between devices on a network. It also blocks brute-force password-guessing attacks. Security experts contend that it retains some of the vulnerabilities of its predecessors.
Windows Random Access Memory. No, not that Windows. This is a type of SRAM that allows whole blocks (windows) of memory to be addressed with just a few commands.
Wireless Session Protocol. A variant of HTTP used for Web browsing over a mobile wireless connection. It creates a wireless session for the connection to each URL, which remains in effect until terminated by the user’s browser. This reduces HTTP-related overhead, hence bandwidth use and the impact of latencies. WSP also acts as the OSI layer 5 (Session) protocol within the WAP framework, opening links between wireless network applications.
Windows Template Library. A Microsoft library of C++ classes for writing Windows applications that make heavy use of COM objects. See ATL, MFC, .NET, STL.
World Wide Web. A very popular use of the Internet. HTML, developed by Tim Berners-Lee at CERN, allows Web sites to present images and multimedia content in addition to text. The later advent of scripting languages such as JavaScript added support for interactive content.
HTTP, created to carry HTML, can also be used to transparently connect WAIS, FTP, Telnet, and Gopher servers. See browser.
What You See Is What You Get. The phrase was popularized by American comedian Clerow “Flip” Wilson (1933-1998). For document-creation software, it’s the claim that the view presented is what the end product – printed document, Web page, image, etc. – will actually look like.