All information herein is the view of the author. Use at your own risk, no warenty of any kind is provided.

I am only able to update the site when I am online. I am only online once in a while, Usually only about once or twice per week.

As such most times the site will be updated about once per week. Some pages are likely to be updated on my local copy when I am not online, so some dates may seem off when updates are uploaded to my site (as the edit date is before the upload date).


This is just a site dedicated to what I do in relation to programming in RISC OS, Retrocomputing, and Long Term computing. The only hope is that someone else finds something useful here.

This site is intended to carry my creations, as well as a few articles I am attempting to write relating to RISC OS programming, as well as some relating to retro-comuting, and a few on the concept of extremely long term usable computing. If you find anything useful, please take advantage, if not that is ok. The content of this site is provided AS-IS without any warenty of any kind.


Beings as I was for a time known of in the USA Amiga and Atari ST world I am often asked why I choose to use and program for RISC OS now. First it should be noted, that I have actually been involved in the USA RISC OS world since the late 1980s (when RISC OS was just getting its feet wet). Unfortunately most of the very small number of USA RISC OS users that were are no longer RISC OS users, most of them dropped out shortly after Acorn closed shop.

As far as why I continue with RISC OS instead of one of the others? Well I have always gained more enjoyment from using RISC OS as well as from coding for RISC OS than the others. There is something about RISC OS that realy speaks to the simplicity that personal computers are supposed to be.

For me many things about how things are done in RISC OS seem more intuitive, more productive, and simpler to do than the equilivents in other Operating Systems. Like not having a standard file dialog in RISC OS, instead we drag and drop directly to the Filer windows (Filer in RISC OS is like Desktop in GEM, or Workbench in Amiga OS). Or the way that interapplication transfer is often done with Drag and Drop.

Then there is the very intuitive API for most things, direct SWI calls to do most of what the OS offers. It is a simple enough API to understand completely, while being rich enough to provide everuthing that applications require.

Click for more about what RISC OS is to me.

About me:

This section is to fill the expected obligation of personal information. I am introverted to the point that I do not like saying to much about myself, though here is some minimal information for those that expect it. The small text with a subdued color is intended to reduce the imphasis of this section.

My name is David Cagle, I have been known by the handles Zerro, D-Zerro, Zerro Below, David S, and DS Zerro in the past. Much of my software that is still floating around shareware/freeware archives was released under one of my handles, most of it being from before 2007. A lot of my older stuff was for Amiga, Atari ST, and Acorn Archimedes computers. Do note that my handles that contain the word Zerro always have the double 'r' intentional misspelling, this is a nod to an event of note from my youth.

I am a paraplegic since 2008. I took a few years off of coding anything to release after my injurry, and then in 2012 I got a Raspberry Pi and began back up in the RISC OS world. It has been a slow restart for me since then.

When I jumped back into doing projects I overloaded myself with to many big projects, this has lead to no releases of note in this last decade. I have a lot of large projects that are at varying degrees of completion, and nothing to show the world for it. As such I am attempting to reduce my focus to just a few large projects until such time as I complete them.

I have had a preference for RISC OS as long as I have used the OS. I did not care very much for Arthur OS that came before RISC OS, though when it even then I already liked BBC BASIC V. Whith RISC OS I learned ARM Assembly Language, a greate assembly language. Then I learned the opcode encodings for ARM, a great instruction set.

In computing I began with an Apple ][+, followed quickly with a Commodore VIC20 then a Commodore 64. When the 16-bitters came around I got first an Atari ST then an Amiga 1000. In 1998 I recieved an Acorn Archimedes 310 some upgrades, and I have focused on ARM ever since. I have had and used PC/AT compatibles, I have had and used Macintosh computers, I have had and used Apple IIgs computers, I have had and used newer Amiga and Atari computers, other than the PC/AT all were great systems, though none of them could hold a torch to the combination of RISC OS and ARM for me. In the later half of the 1980s I had a few lower end computers, including some 6502 trainers, CDP1802 Trainers, and an i8080 trainer.

When I was very young I learned BASIC on the Commodore computers, then Amiga BASIC. Over time I learned 6502 assembly language on the Commodore machines. In the later 1980s I learned i8080 machine language, then CDP1802 machine language. I learned 680x0 Assembly and Machine language on the Amiga. Of course the simplicity of ARM meant that it was a natural assembly language to learn. I have used Pascal, C, QuickBASIC (Macintosh), C++, and a hadful of others, I still use C, Pascal, ARM Assembly, CDP1802 Assembly, 6502 Assembly, and BBC BASIC V.

My interest in computers and programming naturally lead to me getting interested in Digital Electronics design, at first fairly simple stuff, and evolving as I learned more and more. I ended up involved in a multiple issue parallel pipeline research project in university, with my thesis based on a means of implementation that I had inovated as a potential improvement to the basic concept. I had of course implemented a few very simple TTL CPUs before university (what digital kid did not do this back then). I remember that the research implementation that I lead for my thesis at university had to be significatnly modified, as originally I chose to use a RISC subset of the 68000 ISA for the project, though the university could not accept that as they could not get approval for its use from Motorola, so it ended up using the ARMv2 ISA subset, this turned out to be a better fit. The test design being a quad-issue implementation, that could in many cases achive better than 3 instructions per clock in real world code.

After university I worked at a computer store as a 'Software Consultant' for some time. The title just means that when someone had a need for a custom program they would put in a detailed request, I would contact them for additional information and to be clear on the request, then I would write an initial version, verify with the customer that it is what they want, finnish it up and deliver it on them paying the store for the product. So I was essensially a contract programmer for a while. Then my medical issues do to life long problems ended up to the point I could not maintain employment, so I continued to play with fun programming at home.

It goes without saying that I ended up knowning a group of people that were the exception to the norm. Geeks tha love to write there own code, and love to play with the extreme ends, those that see a computer for what they can do with it, with little consern for available software (software can always be written). I did not know that other people looked at commercial software as important in there choice of computers, as we did not see the world that way. I also did not know that many people cared about what commercial games they could get for there computers, as we did not see the world that way. We were more likely to play games written by each other and freely passed around at gatherings than to purchase a game, we were more likely to write simple tools than purchase them, and we always shared our works at the various gatherings that used to be common.

Then came the great fall, the day I was injurred and it was explained to me that the ability to walk was unlikely to be seen in my life again. I focussed all of my attention on learning how to maintain muscle I can not use, how to do everything again, and researching ways that I may be able to get back on my feet. This put me to minimal interaction with the computer programming world for a few years.

In 2011 I found out about an upcoming ARM based computer that would be able to run a free version of RISC OS when launched. Then in 2012 this computer came to be, the Raspberry Pi. I immediately purchased 2 Raspberry Pi model B Single Board Computers on there launch, and fitted them to run RISC OS. As such my use of RISC OS has continued, and in an interesting twist has lead me to research extreme computing situations in recent years.


© David Cagle
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