Operating Systems


ArmOS is a full-featured, prioritized, multitasking, message based, real-time operating system which provides a comprehensive set of system services to the tasks which operate under it. These include process management services, memory management services, interprocess messaging services, timer services, interrupt management services, console services, Networking services, Mutex services, Device services, Storage services, System control services and more. The OS also provides a facility for installable services, so that extensions can be provided which integrate seemlessly with the OS API.

An integrated debugger is incorporated into the OS which provides an isolated context to troubleshoot processor exceptions, memory protection violations, software panics and general softare debugging. The debugger includes standard debug commands (memory examine/modify, CPU/register manipulation, disassembly, breakpoint, single-step etc.) as well as well as functions specific to the operation system, including message/pool auditing, stack callback tracing, and commands to dump OS state, timer, console message, mutex & network queues, as well as internal operating system state variables.

There are two build modes: A debug build incorporates extensive error diagnostics, and traps directly to the debugger in the event of an hardware or software exception. A release build disables the more processor intensive error diagnostics, and automatically recovers from exceptions (It can be set to trap to the debugger so that problems can be diagnosed in the field if needed).

ArmOS employs a device independent driver model allowing it to be deployed on vastly different hardware platforms. It is currently used in line of ARM7 and ARM9 based telephone/voip switching products.


The ArmOS file system is a general purpose file system with a few unique additional capabilities. Although it appears at first glance to be an integral part of ArmOS, it is in fact an independent installed extension/service.

The main features of the ArmOS file system are:


Data Switch Operating System is the proprietary multitasking kernel embedded in a line of small office Data PBX switching systems. It's main features are:


Cubix is a single user operating system that I developed in the 1980s for my 6809 Portable Computer. It's main features are:

The "Dunfield 6809" system and it's software is described in more detail on my classic computing website.


Device Management Facility is a small OS I wrote in the late 1970s for my 8080 based Altair 8800. As the name suggests it was mainly a means of managing the system devices which included the console and several other serial ports, a NorthStar MDS-A disk subsystem and a 9-track tape drive with a handmade controller board.

The main features of DMF are:

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Copyright 2013 Dave Dunfield.