The Altos 586 is an avanced, multi-user computer system with support for up to six users logged into six different accounts at the same time. The Altos 586 ran XENIX, a Microsoft version of the popular UNIX operating system. Optionally, single user CP/M or MP/M-86 could be installed instead.

The case of the machine is sculpted plastic, other manufacturers often chose for sheet metal. This made the machine comparatively light-weight compared to those other computers.

The computer ran on an Intel 8086 CPU clocked at 10MHz. Altos developed its own memory-management technology to counter the poor 8086 memory capabilities. This resulted in an advanced business computer with options that many competitors could not deliver like multi-user OS, networking, and email.

Altos also made an upgraded version of the 586, the Altos 986 that supported up to nine users at the same time.

Xenix was Microsoft’s port of AT&T Unix to microcomputer platforms, beginning in the early 1980s, and represents one of the first serious attempts to bring Unix down from minicomputers and workstations into the 16-bit microprocessor world. It was derived initially from Version 7 Unix and later System III, adapted to run efficiently on hardware like the Intel 8086/8088, Zilog Z8000, and later the Motorola 68000. Unlike MS-DOS, Xenix was a fully preemptive, multitasking, multiuser system, exposing the same hierarchical file system, permissions model, process control primitives, and interprocess communication features familiar from its minicomputer ancestors. For developers, this meant that on relatively modest hardware, one could run a standard C compiler, link editor, assembler, and make use of pipes, redirection, and shell scripting—capabilities nearly absent from DOS at the time.

One of Xenix’s key engineering challenges was adapting Unix’s relatively heavy kernel model to machines with limited RAM and no memory management hardware. The 8086 implementation, for instance, had to work within a segmented memory model, forcing Microsoft’s engineers to fit process address spaces into 64 KB segments and implement kernel/user separation in a constrained way. Despite these limitations, Xenix supported demand-paged swapping, multiple terminals connected via serial interfaces, and block-structured file systems with mountable volumes. Device drivers were modular, and the system could support Winchester hard drives, tape backups, and various terminal types. For systems like the Altos 8600 series, this meant Xenix could handle up to 8 or more users running concurrently, each with their own shell and processes.

From a systems perspective, Xenix was significant because it created a bridge between the proprietary minicomputer Unix systems and the personal computing world. It brought features like multiuser time-sharing, background jobs, and networking primitives (in later releases) to machines typically seen as “single-user” boxes. Many third-party ISVs wrote business applications specifically for Xenix, including accounting packages, word processors, and database systems, leveraging its stability and multiuser design. Although eventually eclipsed by DOS and later Windows in the Microsoft ecosystem, Xenix seeded a Unix culture into the microcomputer world and influenced later efforts such as SCO Unix, which inherited much of Xenix’s base and kept it alive into the 1990s. For retro computing enthusiasts, it remains a fascinating example of Unix squeezed into 16-bit constraints yet still delivering an authentic multiuser Unix environment.

The 8086 CPU from Intel is a 16-bit microprocessor and was designed between 1976 and 1978. The 8086 is the foundation of the x86 cpu architecture which is Intel's most successful line of processors.

The 8086 used the same microarchitecture as the 8-bit 8008, the 8080, and the 8085. This allowed assembly language programs to run seamlesly on the 8086. New instructions and features were added and the bus structure was designed to allow for collaboration with co-processors, such as the 8087 that was released later.

The Z80 quickly became popular in the personal computer market, with many early personal computers, such as the TRS-80 and Sinclair ZX80, using the Z80 as their central processing unit (CPU). It was also widely used in home computers, such as the MSX range, SORD, and the Amstrad CPC, as well as in many arcade games. Additionally, it was also used in other applications such as industrial control systems, and embedded systems. The Z80 was widely used until the mid-1980s, when it was gradually replaced by newer microprocessors such as the Intel 80286 and the Motorola 68000.

The Z80 microprocessor was developed by Zilog, a company founded by Federico Faggin in 1974. The Z80 was released in July 1976, as a successor to the Intel 8080. It was designed to be fully compatible with the 8080, but also included new features such as an improved instruction set, more powerful interrupts, and a more sophisticated memory management system.

Originally the Z80 was intended for use in embedded systems, just as the 8080 CPU. But the combination of compatibility, superior performance to other CPUs of the era, and the affordability led to a widespread use in arcade video game systems, and later in home computers such as the Osborne 1, TRS-80, ColecoVision, ZX Spectrum, MSX, Sega's Master System and many more. The Z-80 ran the original Pac-Man arcade cabinet. The Z-80 was used even in the Game Gear (1990s), and the TI-81 and succeeding graphic calculators.

The Z-80 remained in production until June of 2024, 48 years after its original release. Zilog replaced the processor with its successor the eZ80, an 8-bit microprocessor that features expanded memory addressing up to 16 megabytes, and running up to 50MHz, comparable to a Z80 clocked at 150MHz.

The Intel 8089 Input/Output Coprocessor (IOP), introduced in the early 1980s, was designed as a companion chip to the Intel 8086/8088 CPUs. Its primary purpose was to offload complex I/O tasks from the main processor, enabling more efficient multitasking and data transfer. The 8089 featured its own instruction set, internal registers, and control logic, allowing it to independently manage peripheral devices such as disks, printers, and communication interfaces. By handling I/O operations asynchronously, it reduced CPU overhead and improved system throughput, particularly in multitasking operating systems and environments requiring high-performance data management.

The 8089 could coordinate multiple I/O channels simultaneously, using a specialized structure called Task Blocks to define control parameters for each operation. This design enabled efficient Direct Memory Access (DMA)-like transfers and real-time communication between memory and peripherals without constant CPU intervention. Architecturally, the 8089 was sophisticated for its time, providing mechanisms for priority handling, interrupts, and concurrent task execution. Though not as widely adopted as other Intel support chips, it represented an early step toward intelligent peripheral controllers and laid groundwork for later advancements in bus-mastering I/O and dedicated DMA engines.