Rocky Mountain BASIC (also RMB or RM-BASIC) is a dialect of the BASIC programming language created by Hewlett-Packard. It was especially popular for control of automatic test equipment using GPIB. It has several features which are or were unusual in BASIC dialects, such as event-driven operation, extensive external I/O support, complex number support, and matrix manipulation functions. Today, RMB is mainly used in environments where an investment in RMB software, hardware, or expertise already exists. History and implementations The origins of Rocky Mountain BASIC can be traced to Hewlett-Packard's facilities in Colorado. Since Colorado is located in the Rocky Mountains, this variation of BASIC was dubbed "Rocky Mountain BASIC", to differentiate it from the other BASIC dialects developed within the company. It is unclear if the Rocky Mountain BASIC name was original to HP or came from outside, but HP/Keysight use the term in their own documentation, as well as the more formal "HP BASIC" product name. The HP 9830A, introduced in 1972, was the top of the 9800 line programmable calculator line, which was the first HP computer which fit on a desktop to have a BASIC interpreter in read-only memory (ROM). The interpreter could be extended with ROMs for features like mass storage, plotter graphics, string variables and matrix operations. It had a one-line LED panel for line editing, but was followed in the late 1970s by the faster HP 9835 and HP 9845 desktop computers with full screen CRT displays. These were amongst the first workstations aimed at scientists and engineers for both technical computing and instrumentation control. These were followed by the HP 9826 and HP 9836 computers, which were the leading models of the HP 9800 series of computers. All four of these computers ran versions of Rocky Mountain BASIC. These computers were often used as controllers for HP automatic test equipment, connected via the HP Instrument Bus, (HP-IB). HP wanted to provide a programming language that would be friendly to the engineers and scientists who used such test equipment. The BASIC programming language was chosen, as it was already intended to be easy for novices; knowledgeable users could also program them in assembly language or a version of Pascal. Early implementations of RMB software on the HP 9000 platform were called "HP BASIC/WS". BASIC/WS ran stand-alone. It provided operating system (OS), integrated development environment (editor and debugger), and the language interpreter. Later, HP implemented