interface to other devices, such as QIC-02 tape drives or video cameras. Software The PERQ's original p-Code-like instruction set (called Q-Code) was optimized for Pascal (specifically, an extended PERQ Pascal). Q-Code instructions could be executed at a rate of up to 1 million instructions per second. This gave rise to the alternative definition of the PERQ name: Pascal Evaluation Real Quick. In fact it was generally more efficient to use Pascal than to attempt to create "assembly language" programs directly with Q-Code. Operating systems A variety of operating systems were developed for the PERQ. These included: POS (PERQ Operating System) The initial single-task operating system for PERQ workstations, developed by 3RCC. POS and its utilities were written in PERQ Pascal. MPOS (Multitasking POS) A multitasking version of POS, not officially released by 3RCC. Accent A multitasking research operating system developed at CMU, with a window manager called Sapphire. Accent was a predecessor of the Mach kernel which many later operating systems would use. A UNIX System V-compatible environment running under Accent in a Sapphire window, called QNIX, was developed by Spider Systems. PNX ( ) A port of Unix for the PERQ, based on Seventh Edition Unix and UNIX System III. This was developed by ICL at Bracknell, Dalkeith Palace and later Kidsgrove (Staffordshire) for the UK research community. PNX used its own microcode, more appropriate for the C programming language, called C-Code. FLEX Developed by the Royal Signals and Radar Establishment, FLEX was implemented in microcode and similar to other early workstation systems such as Lisp machines, UCSD Pascal or Modula-2, except that the language of choice was ALGOL 68. Compilers ICL and 3RCC contracted with the Edinburgh Regional Computing Center (ERCC) over 1981-1982 to supply an optimised Fortran77 compiler. This also resulted in an Imp compiler being created, as the F77 compiler from the ERCC was written in Imp. The ERCC compilers generated Q-Code. By 1987, maintenance of the PERQ compiler suite had been taken over by a commercial spin-off group of ex-ERCC employees, Edinburgh Portable Compilers Ltd (EPCL). Applications The PERQ was a popular early graphical workstation; therefore, it helped spawn many early third-party applications that took advantage of the graphical user interface and bitmapped graphics. Intran (around 1982) produced a pioneering graphical program suite called MetaForm, which consisted of the separate Graphics Builder, Font Builder, Form Builder, and File Manager programs. The PERQ also served as