A totally computer‐controlled triple quadrupole mass spectrometer (TQMS) is described. It has a number of unique features not available on current commercial instruments, including: complete computer control of source and all ion axial potentials; use of dual computers for data acquisition and data processing; and capability for self‐adaptive control of experiments. Furthermore, it has been possible to produce this instrument at a cost significantly below that of commercial instruments. This triple quadrupole mass spectrometer has been constructed using components commercially available from several different manufacturers. The source is a standard Hewlett‐Packard 5985B GC/MS source. The two quadrupole analyzers and the quadrupole CAD region contain Balzers QMA 150 rods with Balzers QMG 511 rf controllers for the analyzers and a Balzers QHS‐511 controller for the CAD region. The pulsed‐positive‐ion‐negative‐ion‐chemical ionization (PPINICI) detector is made by Finnigan Corporation. The mechanical and electronics design were developed at LLNL for linking these diverse elements into a functional TQMS as described. The computer design for total control of the system is unique in that two separate LSI‐11/23 minicomputers and assorted I/O peripherals and interfaces from several manufacturers are used. The evolution of this design concept from totally computer‐controlled instrumentation into future self‐adaptive or ‘‘expert’’ systems for instrumental analysis is described. Operational characteristics of the instrument and initial results from experiments involving the analysis of the high explosive HMX (1,3,5,7‐Tetranitro‐1,3,5,7‐Tetrazacyclooctane) are presented.