Systems Engineering Laboratories
Systems Engineering Laboratories (also called SEL) was a manufacturer of minicomputers in Fort Lauderdale, Florida. It was one of the first 32-bit realtime computer system manufacturers. Realtime computers are used for process control and monitoring; to accommodate these applications, they must include architectural features allowing them to respond quickly to external stimuli such as switch closures in a power plant.
Systems Engineering Laboratories was founded in Fort Lauderdale, Florida in the late 1950s by nine engineers from Radiation, Inc., of Melbourne, Florida, at the beginning of the breakout of minicomputers from 16-bit to larger architectures. Their original product was based on a patent for sampling low-level analog signals. A number of data acquisition and control systems (which included no computers) were built for NASA installations.
SEL was purchased by Gould Electronics in 1981 and was operated essentially unchanged as the Gould Computer Systems Division (CSD). Later, in 1989, Encore Computer Corporation (about 250 employees) bought the computer division (about 2500 employees) from Gould. Parts of Encore were sold off over the years, with the last major spin-off being their Storage Products Group, sold to Sun Microsystems in 1997. This left the company consisting primarily of their real-time group (the original SEL core) and returned to this business niche after renaming themselves Encore Real Time Computing. In 2002, Compro Computer Services, Inc.  (a former service competitor, and later service partner) obtained SEL/Gould/Encore real-time technological assets through its acquisition of Encore Real Time Computing, Inc., and continues support of the legacy SelBUS-based product line as far back as the 32/55 and offers an upgrade path using the Legacy Computer Replacement System (LCRS) hardware simulator. Compro Computer Services, Inc continue trading as Encore in Europe, COMPRO continues the tradition of long-term product support by offering replacement solutions (e.g., the Legacy Computer Replacement System, or LCRS) that emphasize backward-compatibility coupled with future-proofing. Gould (as well as its primary competitors MASSCOMP, Harris and Concurrent) were driven into the ground by general purpose microprocessor Unix designs such as those by Sun and SGI.
SEL 800/8000 series
Within a couple of years of its founding, the company's first computer, the 820, was created as a special project for one customer. SEL's early computers, such as the 810A, the 8500, and the 8600, used wire-wrap construction to create the numerous system boards and backplane (called a swingplane). Components were low-scale resistor-transistor logic (RTL) integrated circuits comprising a few transistors per chip, and core memory was used. The 840A used all integrated circuit logic. It had up to 16K of 24-bit word core memory, all directly addressable. Cycle time was 1.75 microseconds. It also had three hardware index registers, priority interrupts with 60 levels, memory parity, and memory protect. By 1967, over 30 840A systems had been sold. Software included the 840A Real-Time Monitor, a FORTRAN IV compiler, MNEMBLER Assembler, Mathematical and Utility Routine Library, and Diagnostic Routines. Supported peripherals included: disc storage (24 Mbit, removable), 45-ips 9-track magnetic tape, card reader, card punch, 300 LPM line printer, and various data acquisition interfaces.
SEL 32 series
In 1975, the Model 32/55 computer was introduced along with a new bus architecture called the SelBUS. This system was the industry's first true 32-bit super minicomputer. The bus speed was 26.6 megabytes per second, which was a record at the time of its introduction. The CPU of the 32/55 was composed of three wire-wrapped boards bolted together. The use of a bus instead of a wire-wrapped backplane simplified manufacturing, lowered costs, and made system enhancements easier. Multilayer printed circuit boards were introduced with the 32/75 about a year later, and single-board CPUs were introduced shortly thereafter. Core memory was replaced by semiconductor memory.
The SEL 32 series became extremely popular in many technical markets such as aircraft simulation, oil exploration, electric power system control, and the beginnings of computer animation. Gould/SEL computers were used to animate the opening sequence for Steven Spielberg's television series "Amazing Stories".
The SEL BUS consists of: 32 bit bi-directional data path, 24 bit address path (16 Mb addressing) + F-bit, interrupt control lines for 128 Max interrupts 32/55 or 112 Max for the 32/75, 6.67 MHz bus clock which gives 150 ns bus transfer cycle time and 6.67 MW/s or 26.67 Mbit/s bus throughput (best case), 28 inch bus length with 38 card slots max, no slot dedication, high speed schottky TTL drivers/receivers, passive termination, I/O cards with on-board DMA contention logic.
SEL 32/8000-9000 series
In the early 1980s, SEL introduced a system based on emitter-coupled logic (ECL) technology code named the Thunderbird. Its official marketing name became the 32/8780 and later the 32/9780. The CPU for this system ballooned to about a dozen boards because of the low-density ECL chip footprint. As a result, CPUs could only be placed at each end of the SELbus, limiting computer systems to two CPUs. It had modular cache memory that could be upgraded. In the mid-1990s, the RSX computer board featured RISC processing capabilities and high speed 75 ns static RAM design (essentially an all-cache design) while maintaining complete binary compatibility with existing programs.
Gould/SEL's "High Speed Data interface" or HSD was considered an industry standard in the process control industry.
One of Gould's primary contributions to the real-time computing world was its "Reflective Memory" technology which allowed up to eight computers to share memory at a very high speed.
When Encore Computer acquired Gould's Computer Systems division, the new Encore switched to using Motorola 88100 series of chips and a Unix-based OS. They built a small Unix based system known as the Encore-91 which included a number of RT extensions including a "micro-MPX environment."
Encore used the real-time reflective memory design from Gould along with their 88100 based systems and Umax OS to create a line of high-density storage devices. Known as the Infinity-90 product these acted as large SANs for Unix, Windows and Mainframe computers with data sharing capabilities. In 1997 Encore sold this product line to Sun Microsystems where it was marketed as the A7000. It was not very successful and eventually canceled by Sun. About 200 Encore employees went to Sun in this exchange.
Because of the long-life support requirements of nuclear plants and military flight simulators, there are still companies in existence today providing support and parts for Gould/SEL systems.
SEL had a proprietary operating system called Real Time Monitor (RTM) which, although extremely fast, had limited user interface. It supported a console for command entry, but no additional users. When the SEL 32 systems were introduced, SEL created another operating system called MPX-32 which supported multiprocessing and multiple users. Later, in the early 1980s, SEL adopted the Unix operating system. As "Gould CSD" (Computer System Division) then introduced the UTX-32 Unix-based OS that included both BSD and System V characteristics. It was one of the first Unix based systems to receive NSA's C2 security level certification.
Moving into general-purpose Unix systems, Gould introduced the NPL (New Product Line) which ran UTX-32 exclusively as was not designed for real-time applications.
Encore's acquisition resulted in a switch to using Encore's Umax, another Unix-based operating-system.
- Surden, Esther; Lundell, Jr., E. Drake (31 Dec. 1975 — 5 Jan. 1976). "Rapid Growth at Top and Bottom of Range Marks Year". Computerworld (Newton, Massachusetts: Computerworld, Inc) 9 (53): 33. Retrieved 9 Nov 2011.