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Apollo/Domain was a range of workstations developed and produced by Apollo Computer from circa 1980 to 1989. The machines were built around the Motorola 68k family of processors, except for the DN10000, which had from one to four of Apollo's RISC processors, named PRISM.

The original operating system was Apollo's own product called Aegis, which was later renamed to Domain/OS. The Domain/OS system offered advanced features for the time, for example typed I/O, network transparency, a graphical user interface and interoperability with BSD, System V and POSIX.

An Apollo workstation resembled a modern PC, with base unit, keyboard, mouse, and screen. Although some designs were in theory oriented for desktop use, in practice they were so bulky that they tended to sit beside the desk anyway. Every Apollo system (even standalones) had to include at least one network interface; the user had a choice between 4 Mbit/s IBM Token Ring, 10 Mbit/s Ethernet, or 12 Mbit/s Apollo Token Ring. Apollo Token Ring was generally the best choice, since it was extremely scalable; whilst the Ethernet of the time suffered serious performance loss as extra machines were added to the network, this was not true of ATR, which could easily have over a hundred machines on one network. One drawback was that, unlike Ethernet, one machine failure (which could easily happen given a single faulty connector) stopped the entire network. For this reason, Apollo provided an optional network cabling system which, at least, allowed machines to be disconnected and moved without problems.

The network orientation of the systems, together with the ATR functionality, made it easy and practicable to boot and run diskless machines using another machine's OS. In principle, as many machines could be booted from one host as it could cope with; in practice, four diskless machines from one host was about the limit. Provided the correct machine-specific software was installed on the host (again, very easy), any type of machine could be booted from any other, the only exception being that a DN10000 could not be booted from a 68K-based system.

Some systems could have the graphics card removed so that they could be used as a servers; in such a case the keyboard and mouse were automatically ignored, and the system accessed either across the network, or via a dumb terminal plugged into the machine's serial port. Such a system was designated "DSP" instead of "DN".

The mainstay of the Apollo range in the mid to late 1980s was the DN3000/4000 series, later upgraded to DN3500/4500. The DN3500 was approximately as powerful as the DN4000. These machines were visually very similar, the base units using the beige boxes typical of PCs of the time. Internally, they used many PC components, including PC/AT expansion slots and PC-compatible disk drives. In principle, a user or third party could install a standard AT expansion card, but since this required the writing of a special device driver, in practice this was very rare. However, the size and design of the boxes made installing or replacing components very easy. A typical system could have between 2 MiB and 32 MiB of memory, a 76 MB, 150 MB or 330 MB (very occasionally 660 MB) hard disk, and 32-bit 68020 or 68030 processor running at 12 MHz to 33 MHz, depending on model. A half-height expansion bay could take either a 5¼-inch floppy disk drive or a QIC-type cartridge tape drive, capacity 30 MB, 45 MB, or 60 MB depending on cartridge. For printer access, the system came with a serial port as standard; a serial/parallel expansion card could provide a parallel printer port if this was required.

PC compatibility was possible either through software emulation, using the optional product DPCE, or through a plug-in card carrying an Intel 80286 processor. A third-party plug-in card with a 386 was also available.

Although Apollo systems were easy to use and administer, they became less cost-effective because the proprietary operating system made software more expensive than Unix software. The 68K processors were slower than the new RISC chips from Sun and Hewlett-Packard. Apollo addressed both problems by introducing the RISC-based DN10000 and Unix-friendly Domain/OS operating system. However, the DN10000, though fast, was extremely expensive, and a reliable version of Domain/OS came too late to make a difference. The increased speed and falling price of PCs ensured the obsolescence of high end system such as Apollo workstations.

In 1989 Hewlett-Packard acquired Apollo. They later released the DN2500 series workstation, a cheap alternative to the DN3x00/4x00 series, and later still the HP 9000 Series 400 line, which could run either HP's own flavor of Unix, HP-UX, or Domain/OS. In this case, the choice had to made at time of purchase, partly because HP-UX and Domain/OS functionality required different keyboards and mice.