Comp.sys.acorn.programmer is a newsgroup for discussion regarding programming RISC OS computer systems. Its remit is wide covering everything from novice programmers to assembly hackers.

You are encouraged to ask any programming questions but be aware that you may find people more knowledgeable in a specific area of programming (e.g. 3D graphics) on a group dedicated to that subject.

First, a reminder of basic netiquette. Before posting a question check that it is not in this FAQ. Then check that it has not been discussed before. Google may be used for this last task.

You may also find an answer to your question in either a RISC OS specific web site (try Acorn Search) or a generic programming resource such as Wotsit.

Finally consider whether your question is appropriate to comp.sys.acorn.programmer. In particular bear in mind that although you are writing your program on a RISC OS machine your question may not be RISC OS specific. In these cases there may be a more appropriate group available.

Having said all that don't be put off posting. As long as the denizens of the group think you have employed due diligence in searching for an answer they will be happy to try and help.

One last thought. Do not end your message with Please reply by private e-mail as I do not read this group. This is considered exceptionaly rude and exploitative. If you can not be bothered to participate in the group, even for the life span of your query, then the regulars can not be bothered to help you.

It is often a good idea to include a code fragment when asking a question as it is often much easier to sort out the problem from the code than from a hand-wavey discription. The golden rule is Keep it short and relevant.

Another trick to make potential helpers' lives easier and increase the likelyhood of you getting a useful reply is to include as much error information as you can. Also outline your debugging effort to date: What you have tried and what did and didn't work.

Code fragments should be included in-line rather than being attached with uucode or MIME. It is also not acceptable to attach binary files to your posts. If you feel that a binary will make matters clearer then upload it to a web site and provide a link to it.

The most obvious languages are BASIC with its built in assembler as these are provided for free with the operating system. There are a number of C/C++ products as outlined in a following question. The Acorn C/C++ package also comes with the ObjAsm assembly language development application. Other languages which have received ports over the years include:

There certainly are:

There was also a C interpreter, is that still available? I think it was written by Hugo Fiennes and came on a magazine cover disc. We have a vote for Acorn User, February 1994.

If you have version 0.76 then you can't, that's the most recent there is.

There is a web site at which further information may be found.

The original Java Virtual Machine (JVM) for RISC OS machines is called RiscCafe and was written by Acorn, therefore it is not currently supported. It supports applets written to the 1.0.2 standard. If you want a copy keep your eyes on the charity stalls at shows or the small ads in magazines.

A newer JVM and support libraries called Kaffe has been made available by the Unix Porting Project.

A coding group called eQ R&D gas recently released an alpha test version of their JVM, Zhaba

A third JVM, called Chockcino, is currently under development. As yet no release date is known.

Two Java compilers exist for RISC OS. The first, guavac, compiles to the 1.1 version of the Java run-time environment. It can be used in conjuction with the libraries supplied with RiscCafe or version 1.1 libraries are available for it. Guavac support has been dropped in favour of Jikes.

The second compiler is a port of Jikes from IBM. It's newer, faster, leaner and smells of peppermint.

In my experience the best way to learn programming is to do it however some tutorials and reference material can be invaliable.

The various Acorn/RISC OS magazines have covered this topic (generally some time ago so you will have to seek out back issues) and I can particularly recomend some of the series run in Risc User. The book Wimp Programming for All is based on these articles and is available on the RISC User in a Nutshell CD-ROM.

You may also be interested in Paul Vigays RISC OS Academy initiative. This is an on-line correspondence course which is to cover BASIC programming as well as a number of other topics including HTML coding. Details of the syllabus and subscription rates are available.

As part of their Select scheme RISC OS Ltd are building up a comprehensively revised and updated set of PRMs. This is available in electronic form from the Select members private site. This is going to be a definitive reference for many things and is another good reason for joining the Select scheme. (I also give excelent false witness, price list is available on request)

There is also a wealth of information for C programmers at riscos.info.

Adam Richardson has collected together a page of useful little odds and ends. It is a short distilate of the PRMs and Style Guide along with some common sense suggestions on good practice.

Much software has been written to ease the process of writing software. Below are listed some of the non language-specific pieces which may prove useful.

It relates to the underlying ARM hardware; the simplest explanation is that the earliest ARM CPUs used a combined program counter/processor status register. This limited the effective address range to 64MB (26-bit code). Later ARM CPUs provide 26-bit compatibility along with extra modes that have separate program counter and status registers (32-bit code).

Some ARM CPUs - such as the one used in the Castle Iyonix - lack the 26-bit compatibility modes. For one thing 26-bit mode is incompatible with the Thumb instruction set provided by some ARM processors.

There is a longer disertation on this topic should you wish some further reading.

Castle sell an improved version of the Norcroft compiler, tools and libraries which includes an addressing scheme agnostic (i.e. it works for both 26 and 32 bit addressing modes) version of the shared C library.

GCC also offers 32-bit addressing mode support as does LCC.

As far as libraries are concerned most have now been updated but check with the original distribution site before assuming that the one you use has.

Chances are you have a space after the THEN. In these cases BASIC will assume that it is dealing with a single line IF. Thus it will execute the rest of the block regardless of the state of the condition.

There are a number of ways of avoiding this problem in the future. Both Zap and StrongEd provide a means whereby trailing spaces may be automatically stripped on file save. Alternatively you can use the BASIC command CRUNCH to perform a number of size reducing operations including the removal of trailing spaces.

Performing this task is a little trickier than you might at first think. It is not simply a matter of *RUNing the new program as doing this will replace the currently executing code with the new stuff. Hence when the new program finishes executing it will exit but the original program is no longer in existence to return to.

There are a number of ways to achieve the desired goal. The hardest, most prone to errors and least recommended method is to fiddle around, a lot, to set up a new environment in which the new program may run.

If you are looking for an easier and less nasty way there are several. There is *WimpTask which will work inside and outside the WIMP. Be warned though that you have to be careful keeping track of which task is swapped in at any given time. If you try to include arguments to the new program by placing them in memory which is then swapped out you can suffer crashes.

There is also the BASICShell module which is part of the SharedBLib library. This module may have trouble if another has claimed certain vectors.

Finally you can try hacking the code which provides this function out of the SlideShow application.