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WELCOME TO THE COMP.SYS.ACORN FAQ MONTHLY UPDATE.

This update is automatically generated by my machine, so please email me at csa-faq@vigay.com if any parts are missing or corrupted. --------------------------------- part 1 of 4 ------------------------------

WELCOME TO THE COMP.SYS.ACORN.* FAQ MONTHLY UPDATE.

This database comprises answers to the most Frequently Asked Questions on the popular Acorn Usenet newsgroup hierarchy, and is maintained by Paul Vigay.

A text based version of this web site is posted to comp.sys.acorn.announce and comp.sys.news.answers on a monthly basis.
This text version consists of four parts of up to 50K each, broken down into the following segments;

Part 1 - Index & section 1 (41K)
Part 2 - sections 2, 3 & 4 (43K)
Part 3 - sections 5, 6, 7 & 8 (49K)
Part 4 - sections 9, 10, 11 & 12 (50K)

If you have any queries, or would like to suggest a new question, please contact me.


Last alterations: 25th Apr 2003
-------------------------------

Recent changes:-
* Changed FAQ email address to faq at vigay.com

Contained below is a list of the most commonly asked questions about Acorn machines in the comp.sys.acorn hierarchy. Before posting to comp.sys.acorn.*, if you are new to the groups, check to see if your question(s) are already answered below. Corrections and/or additions to the list should be sent to faq at vigay.com and I'll try to update the main FAQ as soon as possible....

This FAQ is posted monthly to comp.sys.acorn.misc, comp.sys.acorn.announce, comp.answers and news.answers.

For Web browsers out there, the FAQ home page is http://www.vigay.com/csafaq/. This will always contain the latest version of the FAQ.

Lastly this FAQ is maintained by Paul Vigay. Most of it is copyright Philip R. Banks who created it and maintained it until I took over from him on 1st Dec 1998. Obviously as time progresses and I manage to update and revise sections then copyright will gradually become more and more mine. However, the aim of this FAQ is to share information and help newcomers to the Acorn scene, therefore permission is granted for free distribution of the entire list or quoted segments of it.

If you wish to include segments of the list into other documents then proper attribution must be performed and if you wish to include a part of the list, or the list in full, in any commercial product then express permission must be obtained from myself.

Index of Questions
------------------
The questions have been categorised loosely into related sections, in an effort to make finding the desired information simpler and quicker.

Section 1 - Hardware and Operating Systems

Q1.1) What is an Acorn machine?
Q1.2) What kind of Acorn machines are there?
Q1.3) What versions of the ARM processors are there?
Q1.4) What are the main new features of RISC OS 3?
Q1.5) What are the differences between RISC OS 3.5 and RISC OS 3.6?
Q1.6) What are the differences between RISC OS 3.6 and RISC OS 3.7?
Q1.7) What are the differences between RISC OS 3.7 and RISC OS 3.8/4?
Q1.8) What are the graphics capabilities of the Acorn machines?
Q1.9) Is Virtual Memory possible under RISC OS?
Q1.10) What is the current status of Linux for Acorn machines?
Q1.11) What 'Easter Eggs' are present in RISC OS?
Q1.12) What is the current status of NetBSD for Acorn machines?
Q1.13) What is RISC OS 3.8/Ursula?
Q1.14) What is 'Lazy Task Swapping'?

Section 2 - Upgrades and Expansion

Q2.1) What are the memory limits of the various Acorn machines?
Q2.2) What is a second processor and what second processors are there?
Q2.3) Can PC VGA & Multisync Monitors be added to an Acorn machine?
Q2.4) Are there any Acorn cards for IBM PC or compatible machines?
Q2.5) What is a VIDC enhancer? Will I need one for my new multisync monitor?
Q2.6) What configuration of serial cable should I use for modem work?
Q2.7) How can I get unfiltered sound from an Acorn machine?
Q2.8) Can I connect a SCART monitor to my Acorn machine?
Q2.9) How do I make a Null modem cable?
Q2.10) What are StrongARM dipswitch settings?
Q2.11) Are there any PIC programmers available for RISC OS?

Section 3 - Configuration

Q3.1) What is ADFSBuffers and what is the best setting for it?
Q3.2) How do I enable solid drags in RISC OS 3?
Q3.3) To what size should I partition my Hard Drive?

Section 4 - Hardware Problems

Q4.1) What do the hard drive error numbers mean?
Q4.2) What can I do with a 'Broken Directory' or a corrupt Free Space Map?
Q4.3) What does the power on self-test check?
Q4.4) My Real Time Clock has paused, how do I restart it?
Q4.5) Why doesn't *Speaker work on my machine?
Q4.6) What can I do about my fan making excessive noise starting up?
Q4.7) After fitting the RISC OS 4 upgrade my CD Rom reports 'Drive Empty'.
Q4.8) Occasionally a fairly early model Risc PC will completely hang for no apparent reason, usually when filer windows are redrawn.

Section 5 - Software Issues

Q5.1) Why does DOSFS corrupt my files occasionally?
Q5.2) Where can I obtain the latest version of module X?
Q5.3) What are the current File-type allocation ranges?
Q5.4) Is there a Modula 2 compiler for the Arc?
Q5.5) What Public Domain Languages are available for Acorn machines?
Q5.6) Why does the RO3.5 desktop sometimes revert to the system font?
Q5.7) Why does ChangeFSI display a blank white window, not an image?
Q5.8) What causes the 'nager:Sprites22' error?
Q5.9) Is there a Real Audio or Real Video player for Acorns?
Q5.10) Is there any 'streaming audio' player software available for RISC OS machines?

Section 6 - Viruses

Q6.1) How can I protect against viruses?
Q6.2) Where can I obtain a virus killer?
Q6.3) I have received some information about a virus from a reputable source, it apparently affects Windows, Mac and/or Linux systems, is it perhaps dangerous for RISC OS users too?

Section 7 - Network Resources

Q7.1) What archives/FTP sites are available?
Q7.2) What Acorn related companies are available on the net via email?
Q7.3) What are the submission addresses for comp.{binaries.sources}.acorn groups?
Q7.4) How to retrieve the FAQ from the source...
Q7.5) What WWW pages are out there for Acorn topics?
Q7.6) What Acorn BBS's are there?
Q7.7) Where can I advertise second hand Acorn kit?
Q7.8) Where can I find a user group local to me?
Q7.9) Is there a more detailed Network FAQ available?

Section 8 - Compatibility with other Machines

Q8.1) How compatible with other systems is an Acorn machine?
Q8.2) Is there a BBC BASIC for other machines?
Q8.3) Can I run 65Host on the Risc PC?
Q8.4) Can I read Acorn format discs on a PC?
Q8.5) What software handles files with this extension?
Q8.6) Is there a version of Draw for Windows?

Section 9 - Technical Details

Q9.1) How do I get a faster interrupt timer than the centisecond ones?
Q9.2) How can I create Interlaced GIFs on Acorn machines?

Section 10 - Risc PC PC Card Details

Q10.1) What is the latest version of the Emulator software?
Q10.2) Why does the serial port not work after using the card?
Q10.3) Why do Windows programs give me incorrect colours in a 256 colour mode?
Q10.4) How much memory can I configure for the PC Emulator?
Q10.5) Can I use Win95 with the card?
Q10.6) Can I resize my PC partition?

Section 11 - Hardware Compatibility

Q11.1) What IDE drives work on Acorn machines?
Q11.2) What are the master / slave link settings for my IDE Drive?
Q11.3) Why won't my Western Digital IDE drive won't work after a cold boot?
Q11.4) What works with what?
Q11.5) What specification memory can I use with my RiscPC?

Section 12 - Common Questions about the FAQ

Q12.1) Why do I get the FAQ twice?
Q12.2) Why does the full FAQ have to be posted?
Q12.3) Isn't the FAQ overly long?
Q12.4) If I find something wrong or am unhappy with the FAQ, what do I do?


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Section 1: Hardware and Operating Systems

---------------------------------------------------------------------------- Q1.1) What is an Acorn machine?

Acorn computers are a British built line of computers that started with 6502 based machines and later became based upon ARM (Acorn Risc Machine) processors. Oddly enough Acorn computers were made by the Acorn Computer Group.

Section 1.2 details those machines currently in manufacture and how to fetch a full list of all machines known to have been made by Acorn. Acorn machines are known for their innovation, flexibility and reliability of hardware/software.

In January 1999 Acorn Computers Ltd., was renamed Element-14, focussing more on their Digital TV technology. Element-14 were later purchased by Broadcom Corporation on November 24 2000. More information can be found on their web site at http://www.broadcom.com

The remaining part of Acorn was later sold to Pace Micros, including the remains of their set-top box division. Thus Acorn the company, is technically no more - other than a brand name. Pace subsequently agreed to licence RISC OS, Acorn's powerful wimp-based operating system to a newly formed company called RISCOS Ltd.

RISC OS is now licenced to a number of third party hardware developers around the world, many of which continue to manufacture RISC OS based computers, and have more machines planned for launch later in 2002/2003.

Reading through section 1 should give newcomers to the Acorn scene a reasonable appreciation of what the machines can do by default. They were very strong in education, which was Acorn's primary market. However, in later years, the Acorn group started to make moves into other markets such as the Digital TV market for the future. For those people who wish to see RISC OS in typical use then visiting http://www.geocities.com/~banksp/Power/Acorn/RISCOS.html will provide you with some images and text about using RISC OS.

www.riscos.org is also a good source of information and links to RISC OS software and resources.

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Q1.2) What kind of Acorn/RISC OS machines are there?

The full list of Acorn made machines is now getting somewhat lengthy as many variants and new machines have been launched amd discontinued in the last few years.

As of June 2002, I'm only listing current machines in the actual FAQ, as there are numerous web sites available which detail the history of Acorn & RISC OS computers. The following sites may be useful to find out about past machines. However, I've included some information on various diverse machines (below).

* http://www.geocities.com/~banksp/Archives/MachineLst.html - Philip Banks comprehensive list of Acorn machines.

* http://www.mcmordie.co.uk/acornhistory/acornhistory.shtml - An excellent technical history of Acorn Computers, compiled by Robert McMordie.

* http://home.in.tum.de/~atterer/acorn.html#hard - Richard Atterer's Information about Acorn Computers.

* http://homepage.tinet.ie/~lrtc/computers/acorn_ro/acorn/ - Richard Butler's History of Acorn & RISC OS

What follows is an up to date list of machines currently in production and available.

Acorn RiscPC series
-------------------
This is the latest generation and architecture of Acorn based machines - superseding, but compatible with, the original Acorn Archimedes range of machines. The StrongARM based Risc PC is currently the fastest RISC OS model available and since the demise of the Acorn brand name, is now manufacturered by Castle Technology Ltd. More information on current models can be found on their web site at http://www.castle.org.uk

All of them feature a highly configurable and modular system that makes a bewildering variety of options available. All are founded on the 'second generation' chipset featuring VIDC20, IOMD and the latest StrongARM processor. The 'RPC' range was launched on the 15th of April 1994 with the RiscPC 600 series of machines. The latest 'Kinetic' RPC is some ten times faster than the original 1994 model.

Risc PC machines feature a dual processor card option, the concept of which was first shown in the A540. The unique design of the motherboard allows the machines to have two processors in the system at once, each of radically different types. Simply by plugging a 486/586 processor card in, Windows software can be run on the machine adjacent to native RISC OS programs. Both processors share the system resources and can be allocated memory and the like to use. Memory management has been improved with memory paging always being done in 4K pages.

Further more the podule interface has been extended with DMA to and from podules, extended addressing, 32bit data pathways from the IO system as well as a vastly expanded memory map for each podule. Realtime video from the IO system becomes a reality with high speed and data transfer applications being boosted considerably.

The Kinetic Risc PC is the latest generation of the Risc PC and was launched by Castle Technology as a flagship model of the Risc PC range. It is equiped with all the features of the Risc PC 700 (below) with the addition of;

INTEL StrongARM 233MHz (revision T) processor
Internet Suite, including JAVA
134MB RAM
2MB VRAM
30GB HD
DVD-CD (only CD read is supported under current configurations)
56K modem
RISC OS 4 as standard</small>

The current RiscPC range consists of a variety of machines based around the spec above. It's probably best to check Castle's web site for up to date information on different models.

The Risc Station series
-----------------------
After the demise of Acorn, this is one of the new RISC OS based machines designed around non-Acorn hardware. Risc Stations are currently available in Network, Lite, Lite+ and 'Scorcher' models. A more powerful model - the Risc Station Evolution - is currently in development and a long awaited portable is nearing completion.

For more information, contact Risc Station Ltd at 168 Elliott Street, Tyldesley, Manchester, M29 8DS (tel.+44(0)1942 797777, fax +44(0)1942 797711). Web: http://www.riscstation.co.uk - email: info@riscstation.co.uk

Detailed specification comprises;
Risc Stations are based upon a 56MHz ARM7500FPE (with integrated floating point co-processor) with RISC OS 4 fitted as standard. Notable features of the base system include:
<small>- 8Mb 60ns EDO memory, upgradeable to 256Mb.
- Screen resolution up to 1600x1200x256 colours.
- 6Mb Flash memory containing RISC OS 4 and additional utilities.
- PS2 style keyboard and PS2 3 button mouse input.
- 2 x fast serial ports rated at 460K baud.
- 2 x high speed EIDE ports.
- 2 x PC style game ports with MIDI.
- 10baseT ethernet port with Wake On Lan.
- EPP/ECP fast parallel port.
- IRDA infra-red interface support.
- High density floppy drive port
- 15 pin VGA connector.
- Full 16 bit OPL3 stereo sound sampler & mixer with FM synthesiser, MIDI, Wavetable support and 2 CD mixer ports. 3 x 3.5mm jack sockets for Line in/Mic in/Headphone & speaker out.</small>

Machine differences
neTworx
As base system above.

neTworxHD
As base system, plus 2GB (min) hard drive.

R7500 Lite
As base system, plus 16Mb memory, 4.3GB EIDE hard drive, 48x Atapi EIDE CD Rom Drive.

R7500+ Lite
As base system, plus 64Mb memory, 10.1GB EIDE hard drive, 52x Atapi EIDE CD Rom Drive.

R7500 Scorcher
As R7500+ Lite, plus CD-RW, native support for LS120 & ZIP atapi drives, 60W external speakers.

The Microdigital series
-----------------------
Microdigital are another third-party manufacturer who produce high performance desktop computers based on ARM RISC processors.

The Mico
--------
The Mico is an entry level system used in primary schools, by users upgrading from earlier Acorn models, first time users and converts from other platforms. Whilst the Omega is a high performance system aimed at the business, enthusiast and power user markets, which should be available to purchase sometime during 2002.

Both systems use the reliable RISC OS 4 operating system which is supported by a wide range of professional applications. There are also plans for a Linux port for the Omega.

Detailed specification of the Mico comprises;
- Four layer ATX form printed circuit board</FONT><P>
- Central Processor Unit : ARM 7500FE
- Clock speed 56 MHz
- Hardware floating point
- Hardware DMA
- Memory : Clock speed 64 MHz, 16MB EDO SIMM - RAM expandable to 256 MB via 2 EDO RAM SIMMs, 5MB Flash Memory Operating system + Mico modules, 240 Byte battery backed up CMOS RAM
- Operating System : Risc OS 4.03 - Mico uses a completely standard version of the operating system it has no hardware specific modifications.
- IDEFS 32 bit Hard Disc Management System with data transfer up to 9MB/sec
- 16 bit Audio System :
- CD quality 16 bit stereo digital sound system
- SoundBlaster, SoundBlaster Pro compatible
- 4 USB ports
A full technical description is available from the Microdigital web site at http://www.microdigital.co.uk/micspec.htm

The Omega
---------
It is not my policy to add technical specs to the FAQ until the machines are actually available to purchase. However, the Omega promises to be the most powerful RISC OS based computer ever made. Full specs are available from the Microdigital web site at http://www.microdigital.co.uk/ompg1.htm


Acorn Diversification
---------------------
Acorn, around October 1995, restructured itself into separate companies. Consequently the originating company will be noted by the machine model name, in brackets, from here on down.

Network Computer (Acorn Network Computing)
is the production implementation of the Reference Standard that Oracle commissioned Acorn to specify for Network Computers. In common with the philosophy the default NC does not have any storage devices beyond a smart card, but can be upgraded as required by the customer. Launched August 1996.

4096k Memory (expandable to 16384kb)
IP Stack by default, capable of using extra drives as required.
Smartcard interface by default.
ARM 7500FE processor. (40 MHz)
12 MHz RAM.
4096k OS in ROM.
~35.9 MIPS.

Set Top Box 2 (Online Media)
an advanced networked computer designed to provide an interactive TV station in the home. These machines require high capacity networks to operate and as such are, as of early 1997, limited mostly to trials in selected areas. These machines feature hardware MPEG decoders as well as an infrared remote for controlling it.
Strictly speaking these machine are no longer quite computers but are more converging into versatile home appliances. Launched July 1996.

2048k Memory (expandable to 32768kb)
CDFS by default.
Optional CDROM drive.
ARM 7500FE processor. (32 MHz)
12 MHz RAM.
4096k OS in ROM.
~28.7 MIPS.

Stork (Acorn Risc Technologies)
the successor to the A4 this is effectively a RiscPC in portable form. There are a few improvements over the capabilities of the RiscPC range including a PCMCIA interface. It is unique in being the first Acorn portable to offer a docking station arrangement. Not launched initially as a product it has been more a licensable design available for volume customers to order as required. A by product of this is that design is somewhat mutable featuring at least two types of LCD screen chosen as required by the customer.
The design has been available since mid 1996.

8192Kb Memory (expandable to 256Mb)
ADFS by default.
IDE interface. (425 Mb)
ARM 7500 processor. (32 MHz)
12 MHz RAM.
4096k OS in ROM.
~29 MIPS.

NewsPAD (Acorn Risc Technologies)
perhaps the most unusual of the portable offerings from ART this is a graphics tablet arrangement of portable with no integral keyboard offered. Rather input is through an inbuilt touchscreen overlayed on the colour LCD display. Two PCMCIA slots are available along with 496 bytes of non-volatile RAM, compared with the more usual 240 bytes offered. A docking station provides parallel, external monitor, serial, keyboard and mouse ports along with a floppy disc drive.
Available since Mid 1996.

8192Kb Memory (expandable to 256Mb)
ADFS by default.
IDE interface. (420 Mb)
ARM 7500 processor. (40 MHz)
12 MHz RAM.
4096k OS in ROM.
~35.9 MIPS.

StrongARM RiscPC (Acorn Risc Technologies)
basically the 700 series machine with larger hard drives, RISC OS 3.7 and a StrongARM (202 MHz) in them. Released September 1996.

Acorn Reunification
-------------------
As part of an image strengthening procedure Acorn reconsolidated to present one company image to the world. Therefore the machines below will simply be referred to as 'Acorn' machines now.

A7000+ is an updated version of the 'entry level' A7000 machine, as the name implies. Keeping the same styling as the A7000 it is notable especially for two features. The presence of a hardware floating point processor by default and the ability to use EDO RAM. Both are firsts for Acorn equipment and hopefully signal a trend in Acorn's design priorities.
Launched 18th of May 1997 at the Wakefield Show.

8192Kb EDO Memory (expandable up to 136Mb)
ADFS by default.
IDE interface. (1.2 Gb hard drive)
ARM 7500 FE processor. (48 MHz)
32 MHz RAM.
4096k OS in ROM.
~43.08 MIPS.</small></tt>

StrongARM RiscPC (Alpha variant) basically the same as it's earlier incarnation but with a 233 MHz StrongARM in it rather than a 202 MHz one.
Released 10th September 1997. (see above for more information on current models)

CoNCord , an uprated NC this is a StrongARM powered machine with expanded memory and Java built in by default. In a break with previous NC designs a Tower configuration has been used with a custom rounded case. Like other NC designs the CoNCord features a ROMCard interface for upgrading the OS as required and an infra-red interface for armchair control.
Launched 7th October 1997.

4096k Memory. (Expandable to 256 Mb, comes with 2 Mb VRAM as well)
IP Stack by default, capable of using extra drives as required.
Smartcard interface by default.
Digital SA110 processor. (233 MHz)
16 MHz RAM.
8192k OS in ROM.
~233 MIPS.

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Q1.3) What versions of the ARM processor are there?

The details of currently ARM chips and their capabilities are described on Philip Banks web site at http://www.geocities.com/~banksp/Archives/ARMChips.html
Current developments can be found on ARM Ltd's web site at http://www.arm.com

----------------------------------------------------------------------------

Q1.4) What are the main features of RISC OS 3 over RISC OS 2?

This information is now contained on Philip Banks email server. If you wish to know the 'new' features of RO3 over RO2 then send a request to his email server, as detailed at the start of the FAQ, for the filename 'RO3diffs'.

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Q1.5) What are the differences between RISC OS 3.5 and RISC OS 3.6?

Quite a few, although nothing particularly drastic OS wise, mostly improvements although the lifting of the FileCore partition limit and the incorporation of JPEG handling into the OS are quite substantial improvements. Here is the list :-

* Now stored on 2x2Mb ROMs, or an increase ot a potential 4096Kb of OS.
* FileCore improvements allowing at least 4Gb partitions.
* Support for ATAPI style CD-ROM drives.
* JFIF handling incorporated into the OS.
* Standard applications have been moved back into ROM.
* Toolbox modules, the Cv5 support modules, moved into ROM.
* CDFS modules moved into ROM.<li>Access modules moved into ROM.

----------------------------------------------------------------------------

Q1.6) What are the differences between RISC OS 3.6 and RISC OS 3.7?

Like RISC OS 3.6, RISC OS 3.7 is primarily changed behind the scenes and is an incremental improvement of the OS. The changes mostly have been geared towards rendering the OS StrongARM compatible. Here is the list :-

* Autodetection of processor type enhanced to detect and cater for ARM6 and better processors up to the StrongARM
* Memory handling has been moved into the kernel, away from the Window manager. This not only speeds up task switching but now means the kernel is now aware of multiple applications.
* FileSwitch supports 2048 byte buffers, useful for CDFS.
* The Font Manager is now capable of blending anti-aliased fonts to a variable colour background. Improving the readability of fonts displayed over colour images. (Like Web pages, say. :) )
* An improved Internet module is supplied in ROM.
* A StrongARM compatible Econet module is supplied in ROM.

----------------------------------------------------------------------------

Q1.7) What are the differences between RISC OS 3.7 and RISC OS 3.8/4?

RISC OS 3.8 was a developmental version of RISC OS 4 released to developers just before the closure of Acorn's Workstation division and cancellation of the Phoebe project. It was code-named Ursula (which is the name of Phoebe's twin sister in Friends!).

It has now been completed by the newly formed RISCOS Ltd and RISC OS 4 is the first new version of RISC OS to be released by a company other than Acorn, A comprehensive list of features was released onto their own web site during April 1999. This can be obtained from http://www.riscos.com/risc_os_4/Features.html

In a nutshell some of the major new features are:-

* Performance Enhancements
* New Disc format brings new features, improved performance and more disc space.
* Redesigned icon set
* Faster/Easier configuration and !Boot
* New screen saver system
* 'Lazy Task Swapping'
* Improved applications including a new !Writer appliction for simple word processing and !Taborca - an Adobe PDF creator.

----------------------------------------------------------------------------

Q1.8) What are the graphics capabilities of the Acorn machines?

All the Acorn machines are highly upgradeable so that they can achieve colour depths and resolutions beyond what is listed here. What is listed here is the default capabilities of the machines as supplied by Acorn. As such it should be taken as a guide to the minimum abilities of the hardware.

8 bit machines
--------------
This covers the BBC Model B, BBC Model B+, Master 128 and ABC range of machines. The display hardware was based on the 6845CRTC chip and was highly flexible for it's time. Resolutions possible :-
X res. Y Res Colours
640 256 2
320 256 2,4
160 256 4,16

As well a Teletext character graphics mode and two text only modes were provided by default. The palette range was 16 colours with modes using less than 16 colours capable choosing any mix of the 16 colours, up to the number displayable of course, for display.

8 MHz ARM based machines
------------------------
This is the original Archimedes range of machines and covers the A300 series, A400 series, R140 and A3000 machines. The increased capability of the VIDC1a chip dramatically enhanced the resolutions and colours depths possible, namely :-
X res. Y res. Colours
160 256 4,16,256
320 256 2,4,16,256
640 250 4,16
640 256 2,4,16,256
640 480 2,4,16,256
1056 250 16
1056 256 16,256
1152 896 2

As can be seen this quite a wide variety of default screen modes. Most are provided to allow driving the various kinds of monitors out there easier, since they are suited to that monitor. The palette range was 4096 colours (12 bit) but the VIDC1a only had 16 hardware palette registers. This meant that in screen modes with sixteen colours or less then the colours could be mapped to any of the 4096 available. However in 256 colour modes 4bits of the colour data are hardware derived and cannot be adjusted. The net result was in a 256 colour a block of 16 colours could be assigned as desired with that block of 16 covering a range of the 4096 available colours.

12 MHz ARM based machines
-------------------------
This covers the A3010, A3020, A4000, A4, A5000, A540 & R260 machines. Here the VIDC1a was still used but it had an extra oscillators added and the primary oscillator was faster (32 MHz) giving finer pixel resolutions. The extra oscillator provided true PC VGA style compatibility for monitors instead of a 24 MHz 'faked' version which sometimes caused problems with intolerant VGA monitors.
X res. Y res. Colours
160 256 4,16,256
320 256 2,4,16,256
640 200 2,4,16,256
640 250 16
640 256 2,4,16,256
640 352 2,4,16,256
640 480 2,4,16,256
640 512 2,4,16,256
768 288 2,4,16,256
800 600 2,4,16
800 352 2,4,16,256
1056 250 16
1056 256 16,256
1152 896 2

Because the display hardware was essentially the same as the 8MHz machines' the palette handling was identical.

Risc PC machines
----------------
his covers all Risc PC in the Risc PC 600, Risc PC 700, A7000 & A7000+ machines. Here the newer VIDC20 chip has been used and the display capabilities are somewhat extended. Namely :-
X res. Y res. Colours
160 256 4,16,256
320 256 2,4,16,256
640 200 2,4,16,256
640 250 4,16
640 256 2,4,16,256
640 352 2,4,16,256
640 480 2,4,16,256
640 512 2,4,16,256
768 288 2,4,16,256
800 600 2,4,16,256,32k*,16M**
896 352 2,4,16,256
1024 768 16,256*,32k**
1056 250 16
1056 256 16,256
1152 896 2
1280 1024 4,16*,256**
1600 1200 16*,256**
* Requires 1 MB of VRAM
** Requires 2 MB of VRAM

With the addition of Video RAM (VRAM) to the Risc PC the base capabilities are a touch variable, thus the note next to some of entries.
All other modes are available with standard DRAM, and these the only modes the A7000 can access. The A7000+, thanks to it's faster memory speeds, functions equivalently to a RiscPC with 1 Mb of VRAM even though it doesn't have any VRAM itself.

Furthermore the new VIDC20 has 256 palette registers, compared to the VIDC1a's 16, and a palette range of 16 million colours. Exactly how the colour mapping in 32,000 modes is handled is not yet clear. Again these are just standard screen modes provided, and even perhaps not all of them - the Risc PC is completely configurable in display resolutions and capabilities.

However each monitor type must have a mode definition file set up for it, to allow you to take advantage of this flexability. A library of common monitor definition files can be found at http://acorn.cybervillage.co.uk/mdf.htm

It must be stressed again that these are merely the resolutions and colour depths defined by the machines operating systems. In all of the machines cases there are both hardware and software extensions that alter and increase the list.

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Q1.9) Is Virtual Memory possible under RISC OS?

Short answer, full VM is not possible under the current versions of RISC OS. The problem is that most of RISC OS works in SVC mode, if a DataFetch abort occurs then R14_svc is corrupted. This makes returning from the SWI somewhat problematic. This is a hardware limitation with the ARM2 and ARM3 cell chips. Hardware using ARM6 or better processor cells have special memory abort modes that alleviate this problem so future machines and incarnations of RISC OS may well have VM available. Indeed the new RiscPC machines make prime candidates for having virtual memory, however there are still re-entrancy issues that make this problematic for RISC OS. (Consider loading data from a file into paged out virtual memory...)

However limited solutions are available now. !Virtual is one such solution allowing VM for a user process using a limited subset of SWI's that are carefully 'protected' against R14_svc being corrupted. Such solutions suffer from the restricted set of SWI's they support and are mostly useful for batch style processing jobs like compilation or memory intensive processing jobs.

!Virtual currently does not work with Risc PCs due to the fact that it requires a page size which is a multiple of 8kb. (This means !Virtual will not work with A305s.)

Also available commercially, from Clares Micro Supplies, is Virtualise for the RiscPC machines. This provides virtual memory on dynamic areas. As more and more software starts to use dynamic areas for data storage and manipulation this will become increasingly useful.

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Q1.10) What is the current status of Linux for Acorn machines?

Due to the rapid development of Linux exact details about the latest incarnation of Linux are not kept in this FAQ. However for the latest information you might like to consult these web pages, or email the people involved with the port :-

Native Linux page :-
http://www.arm.uk.linux.org/ (rmk@arm.linux.org.uk)

Additional information can be obtained from Aleph 1, who are now developing a complete ARMLinux distribution. Further information can be obtained from http://www.aleph1.co.uk

If you have the original Acorn Clan disc and would like to install ARMLinux, I have written a Dummies Guide to Installing ARMLinux which is available at http://www.vigay.com/riscos/armlinux.html

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Q1.11) What 'Easter Eggs' are present in RISC OS?

It has been a long tradition with Acorn OSes to have hidden sections that give credit to the people involved in the creation of that OS. The BBC Model B ROMs had the names of the people involved hidden in the memory space occupied by Fred, Jim and Shelia. With the release of the ARM powered machines this tradition has continued on.

RISC OS 2.00
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* tucked away in the ROMs is a list of the names of involved people.

RISC OS 3.00
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* If you type 'rmtmd' when the desktop welcome screen is displayed a slide show of the key RISC OS team members is displayed on the screen.

* In the info box of the task manager if you clicked menu over the letters 'rmtmd', in that order, contained within the author icon a full list of the people involved with the OS's development is displayed in that icon.

RISC OS 3.10 & 3.11
-----------------------
* In the info box of the task manager if you clicked menu over the letters 'team', in that order, contained within the author icon a full list of the people involved with the OS's development is displayed in that icon.

* Using a template editor examine the task managers templates file from the Resources filing system. (Resources:$.Resources.Switcher.Templates)<li>Inside the 'power' dialogue is a message.

RISC OS 3.50
------------
* In the info box of the task manager if you clicked menu over the author icon four times a full list of the people involved with the OS's development is displayed in that icon. (This can take a while to watch, be warned...)

* Using a template editor examine the task managers templates file from the Resources filing system. (Resources:$.Resources.Switcher.Template3D) Inside the 'power' dialogue is a message, in 3D. This message also appeared in the replacement templates supplied with NewLook for RISC OS 3.1.

REM Extract Names and Pictures from RISC OS 3.50, 3.60 and 3.70 ROMs
REM
REM Based on an original program (for RISC OS 3.50) by Nick Craig-Wood.
REM Updated by Matt Rix <BigRISC@CyberJunkie.Com>
SYS "OS_Byte",129,0,255 TO ,version%
CASE version% OF
WHEN &A5: S=&1F47AC :REM RISC OS 3.50
WHEN &A6: S=&358F18 :REM RISC OS 3.60 - Thanks to Terry Adams for finding this
WHEN &A7: S=&3A0868 :REM RISC OS 3.70
OTHERWISE: ERROR 0,"Cannot run on this ROM version.":END
ENDCASE
S+=&3800000
E=S+&3130
O=65536

SYS "Squash_Decompress",%1000,-1 TO Q
DIM R Q,P O
SYS "Squash_Decompress",%0100,R,S,E-S,P,O TO,,,,,U

path$="Pipe:$."
piccy$=path$+"Pictures"
names$=path$+"Names"
run$="Filer_Run "

SYS "OS_File",10,piccy$,&FF9,,P+8,P+P!4+8
SYS "OS_File",10,names$,&FFF,,P+P!4+8,P+O-U

OSCLI "SetType "+piccy$+" Sprite"
OSCLI "SetType "+names$+" Text"

OSCLI run$+piccy$
OSCLI run$+names$
END

RISC OS 3.60
------------
* In the info box of the task manager if you clicked menu over the author icon four times a full list of the people involved with the OS's development is displayed in that icon. (This can take a while to watch, be warned...)

* Using a template editor examine the task managers templates file from the Resources filing system. (Resources:$.Resources.Switcher.Template3D) Inside the 'power' dialogue is a message, in 3D. This message also appeared in the replacement templates supplied with NewLook for RISC OS 3.1.

* Run the program listed in the RISC OS 3.50 section to be given a list, and pictures, of the primary developers of RISC OS 3.60.


RISC OS 3.70
------------
* In the info box of the task manager if you clicked menu over the author icon four times a full list of the people involved with the OS's development is displayed in that icon, including a 'special' acknowledgment to Peter Bondar. (This can take a while to watch, be warned...) This only works if the menu was opened from the Task Manager window, not the icon.

* Using a template editor examine the task managers templates file from the Resources filing system. (Resources:$.Resources.Switcher.Template3D) Inside the 'power' dialogue is a message, in 3D. This message also appeared in the replacement templates supplied with NewLook for RISC OS 3.1.

* Run the program listed in the RISC OS 3.50 section to be given a list, and pictures, of the primary developers of RISC OS 3.70.

RISC OS 3.71
------------
* In the info box of the task manager if you clicked menu over the author icon four times a full list of the people involved with the OS's development is displayed in that icon, including a 'special' acknowledgment to Peter Bondar. (This can take a while to watch, be warned...) This only works if the menu was opened from the Task Manager window, not the icon.

RISC OS 4.02
------------
* From BASIC, issue the command SYS "OS_Module",2,"IRQUtils" and RISC OS will launch an invaders game.

* Click MENU over the RISC OS 4 icon on the far right of the iconbar. Move the pointer over to 'Info' and then across to open the RISC OS 4 information box. Click MENU four times over the icon containg '© 1999, RISCOS Ltd'. Sit back and watch a list of RISCOS Ltd. developers scroll by.

* Using a template editor examine the switcher module's file in the Resources filing system. (Resources:$.Resources.Switcher.Templates) Inside the 'power' dialogue is the message "Help! We've been released from the software factory, and don't know what to do!". There is another one inside the 'Confirm' template. :-)

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Q1.12) What is the current status of NetBSD for Acorn machines?

N.B. The RiscBSD name has been dropped entirely in favour of NetBSD/arm32.

Due to the rapid development of NetBSD exact details about the latest incarnation of it are not kept in this FAQ. This is a port of NetBSD, a Unix variant, to the RiscPC. However for the latest information you might like to consult these web pages, listen to the NetBSD email list or email the people involved with development of it:-

NetBSD/arm32 - For RiscPC and later machines - http://www.netbsd.org/Ports/arm32/

NetBSD/arm26 - For Archimedes and other pre arm600 boxes - http://www.netbsd.org/Ports/arm26/

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Q1.13) What is RISC OS 3.8/Ursula?

Before Acorn decided to abandon Workstations and focus on Digital TV, work was at an advanced stage on an updated version of the operating system (codenamed Ursula) to live in their new machine (Phoebe). Developers had access the RISC OS 3.8 (as Ursula declared itself to be) for evaluation and beta testing purposes. Versions of RISC OS 3.8 were primarily available for ARM710 machines, although some StrongARM compatible versions are known to exist.

For those who don't know, Phoebe is a character from the hit US sit-com Friends, and Ursula is the name of Phoebe's twin sister.

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Q1.14) What is Lazy Task Swapping ?

On RISC OS 3.5 and 3.6 machines there were seen to be serious delays in the desktop when running applications with large wimpslots, mostly indicated by the lack of reponsiveness. The problem was identified as being that of having to page in the entire application which, with a 4k page size was quite slow. In RISC OS 3.7 this situation was improved by changing the way in which the application is paged in.

RISC OS 4 can support a new method of paging tasks in - Lazy Task Swapping. This can also be called 'demand paging', because instead of paging the entire space in, individual pages are only given 'on demand'. This means that in a large application only sections of the application space may be physically present although the application itself will be unaware of this.

There is a problem, however, with some versions of the StrongARM processor which will (under certain circumstances) cause Lazy Task Swapping to fail. StrongARMs prior to revision T exhibit this failing and Lazy Task Swapping is consequently be disabled. You may also want to disable Lazy Task swapping if you encounter problems when using DMA.

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- Comp.Sys.Acorn FAQ ---------------------------------- End of part 1 of 4 -

This FAQ is maintained by Paul Vigay (csa-faq@vigay.com)
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