M technology

MUMPS (Massachusetts General Hospital Utility Multi-Programming System), or M, is a general-purpose computer programming language that provides ACID (Atomic, Consistent, Isolated, and Durable) transaction processing. Its differentiating feature is its "built-in" database, enabling high-level access to disk storage using simple symbolic program variables and subscripted arrays, similar to the variables used by most languages to access main memory.

The M database is a key-value database engine optimized for high-throughput transaction processing. As such it is in the class of "schema-less", "schema-free," or NoSQL databases. Internally, M stores data in multidimensional hierarchical sparse arrays (also known as key-value nodes, sub-trees, or associative memory). Each array may have up to 32 subscripts, or dimensions. A scalar can be thought of as an array element with zero subscripts. Nodes with varying numbers of subscripts (including one node with no subscripts) can freely co-exist in the same array.

Perhaps the most unusual aspect of the M language is the notion that the database is accessed through variables, rather than queries or retrievals. This means that accessing volatile memory and non-volatile storage use the same basic syntax, enabling a function to work on either local (volatile) or global (non-volatile) variables. Practically, this provides for extremely high performance data access.

Originally designed in 1966 for the healthcare industry, M continues to be used today by many large hospitals and banks to provide high-throughput transaction data processing.

MUMPS was developed by Neil Pappalardo, Robert Greenes, and Curt Marble in Dr. Octo Barnett's animal lab at the Massachusetts General Hospital (MGH) in Boston during 1966 and 1967.

The original MUMPS system was, like Unix a few years later, built on a spare DEC PDP-7. Octo Barnett and Neil Pappalardo were also involved with MGH's planning for a Hospital Information System, obtained a backward compatible PDP-9, and began using MUMPS in the admissions cycle and laboratory test reporting. MUMPS was then an interpreted language, yet even then, incorporated a hierarchical database file system to standardize interaction with the data.