Mike F. Cowlishaw is a Visiting Professor at the Department of Computer Science at the University of Warwick, and a Fellow of the Royal Academy of Engineering. He is a retired IBM Fellow, and was a Fellow of the Institute of Engineering and Technology, and the British Computer Society. He was educated at Monkton Combe School and The University of Birmingham.
Cowlishaw joined IBM in 1974 as an electronic engineer but is best known as a programmer and writer. He is known for designing and implementing the REXX programming language (1984), his work on colour perception and image processing that led to the formation of JPEG (1985), the STET folding editor (1977), the LEXX live parsing editor with colour highlighting for the Oxford English Dictionary (1985), electronic publishing, SGML applications, the IBM Jargon File IBMJARG (1990), a programmable OS/2 world globe PMGlobe (1993), MemoWiki based on his GoServe Gopher/http server, and the Java-related NetRexx programming language (1997).
Cowlishaw has worked on aspects of decimal arithmetic; his proposal for an improved Java BigDecimal class (JSR 13) is now included in Java 5.0, and in 2002, he invented a refinement of Chen–Ho encoding known as densely packed decimal encoding. Cowlishaw's decimal arithmetic specification formed the proposal for the decimal parts of the IEEE 754 standard, as well as being followed by many implementations, such as Python and SAP Netweaver. His decNumber decimal package is also available as open source under several licenses and is now part of GCC, and his proposals for decimal hardware have been adopted by IBM and others. They are integrated into the IBM Power6 and IBM System z10 processor cores, and in numerous IBM software products such as DB2, TPF (in Sabre), WebSphere MQ, operating systems, and C and PL/I compilers.
Cowlishaw wrote an emulator for the Acorn System 1, and collected related documentation. Outside computing, he caved in the UK, New England, Spain , and Mexico  and continues to cave and hike in Spain. He is a life member of the National Speleological Society (NSS), wrote articles in the 1970s and 1980s on battery technology and on the shock strength of caving ropes, and designed LED-based caving lamps. His current programming project is MapGazer .