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- Xref: demon comp.sys.acorn.announce:70 comp.sys.acorn:8430 comp.answers:2400 news.answers:6846
- Path: demon!uknet!EU.net!uunet!comp.vuw.ac.nz!actrix.gen.nz!khantazi!banksie
- Date: Wed, 1 Jun 1994 01:17:11 +1200
- From: banksie@khantazi.actrix.gen.nz (Philip R. Banks)
- Newsgroups: comp.sys.acorn.announce,comp.sys.acorn,comp.answers,news.answers
- Subject: Comp.Sys.Acorn FAQ List Posting (Automatic)
- Keywords: Frequent Questions Answers
- Message-ID: <7JJwWNj030n@khantazi.actrix.gen.nz>
- Reply-To: banks_p@kosmos.wcc.govt.nz
- Followup-To: comp.sys.acorn
- Organization: My Arc.
- Approved: aglover@acorn.co.uk,news-answers-request@mit.edu
- Lines: 1449
-
- Archive-name: acorn/faq
-
- Comp.Sys.Acorn FAQ List. Last alterations 21/May/1994
- -----------------------------------------------------
-
- ----------------------------------------------------------------------------
- Recent alterations :-
- Q29 ammended.
- Q26 address added for Clares.
- Q21 updated with an expanded error list.
- ----------------------------------------------------------------------------
-
- Contained below is a list of the most commonly asked questions about
- Acorn machines in comp.sys.acorn. Before posting to comp.sys.acorn, if you
- are new to the group, check to see if your question(s) are already answered
- below. Corrections and/or additions to the list can be emailed to :-
-
- banks_p@kosmos.wcc.govt.nz
-
- And I'll try to add them as soon as possible....
-
- When reading this FAQ List it is reccomended that you use a text editor
- if you are not interested in reading every question's answer. Each answer is
- seperated by a line of '-' characters. To find the answer you are interested
- in try searching for (in !Edit) "--\x0AQ##)" using Magic characters where ##
- is the question number you are interested in the answer to. This will leap
- directly to the answer.
-
- The posted sections of the FAQ is available from an email server at MIT.
- To request the FAQ from this server send an email to
- mail-server@rtfm.mit.edu. No subject is needed and the body should be :-
-
- send /pub/usenet/news.answers/acorn/faq
-
- Also stored there is Gerben Vos's Acorn Archive list. This can be obtained
- in a similar manner to the faq with the email body being :-
-
- send /pub/usenet/news.answers/acorn/archives
-
- Finally sections of this FAQ are stored in another email server to reduce
- bandwidth when posting it due to these sections being commonly asked but not
- quite often enough to warrant the continual posting. To obtain these
- sections from the email server send mail to the address
- 'banks_p@kosmos.wcc.govt.nz' with the subject (case and spelling important
- ignore the quotes.) "ServerMail". The body of the message should be of the
- form :-
-
- Start:
- [line-limit: <x lines per message>]
- Section: FAQData
- Send: <filename>
- End:
-
- All commands in the body of the message are case insensitive. The line-limit
- command is completely optional and multiple send commands are possible if
- you to request more than one file at a time.
-
- Please remember that this server is a) in Beta test. I only coded it
- recently and there may be some lurking bugs in it yet. & b) at the other end
- of a 2400 baud modem. Thus frivoulous requests for large files will not be
- appreciated. Also if you get the Subject lines case or spelling wrong that
- email will be sent to me instead of the server. Not unsurprisingly I
- probably won't be terribly appreciative to receive email server requests in
- my personal email section...
-
- Index of Questions
- ------------------
-
- Q1) I have obtained [PD] program X but find it needs [version Y.YY of]
- module Z, which I don't have. Where can I get it?
-
- Q2) What version of module X can I assume that all users have?
-
- Q3) What's the minimum version of module X that my program needs? What
- features were introduced/what bugs were fixed in which versions?
-
- Q4) When using DOS discs I often find the last parts of files haven't been
- written correctly, what am I doing wrong?
-
- Q5) Why have there been no postings to comp.{binaries,sources}.acorn
- recently?
-
- Q6) What archives/FTP sites are available?
-
- Q7) How can I protect against viruses?
-
- Q8) Where can I obtain !Killer?
-
- Q9) What is a VIDC enhancer? Will I need one for my new multisync monitor?
-
- Q10) What are the main new features of RISC OS 3?
-
- Q11) How do I enable solid drags in RISC OS 3?
-
- Q12) What kind of Acorn machines are there?
-
- Q13) What are the memory limits of the Acorn machines?
-
- Q14) What is a second processor and what second processors are there?
-
- Q15) Are there any cards for IBM PC or compatable machines that Acorn have
- produced?
-
- Q16) What configuration of serial cable should I use on my Arc for modem
- work?
-
- Q17) Can PC VGA Monitors be added to an Archimedes?
-
- Q18) What is ADFSBuffers and what is the best setting for it?
-
- Q19) What is the current File-type allocation ranges and why won't Acorn
- provide a full file-type list?
-
- Q20) My disc gives me a 'Broken Directory' or my Free Space Map is corrupt,
- what can I do?
-
- Q21) My hard drive gives me disc errors when I use, what do the error
- numbers mean?
-
- Q22) What does the power on self-test check and how does it signal errors
- back to you?
-
- Q23) Is there a Modula 2 compiler for the Arc?
-
- Q24) Is Virtual Memory possible under RISC OS?
-
- Q25) How compatible with other systems is an Archimedes?
-
- Q26) What Acorn related companies are available on the net via email?
-
- Q27) What versions of the processor are there and what are their
- capabilities?
-
- Q28) What are the graphics capabilities of the Acorn machines?
-
- Q29) What are the differences between RISC OS 3.5 and RISC OS 3.11 & 3.10?
- ----------------------------------------------------------------------------
- Q1) I have obtained [PD] program X but find it needs [version Y.YY of]
- module Z, which I don't have. Where can I get it?
-
- All patch modules and current versions of Clib and its ilk are sited on
- the NZ info-server and can be obtained from there if you are sited in NZ.
- Ideally your dealer will also have copies of them too and you should be
- able to obtain them from them. (If they don't you may like to pass on the
- ones from the info-server if you request them, so that they are up to-date.)
- Finally some versions of the patch modules (mostly the newer ones for RISC OS
- 3) are sited at the Acorn ftp site. In the future it is expected that the
- Acorn ftp site will become the primary place for sourcing the current module
- version on the internet.
-
- ----------------------------------------------------------------------------
- Q2) What version of module X can I assume that all users have?
-
- Currently the version numbers are :-
- Clib v3.75
- Colours v0.52
- FPEmulator v2.80
- IRQUtils v0.12
- Hourglass v2.02
- Sound v1.13
- WimpUtils v0.04
-
- All of these modules are only needed if you intend running your
- applications on RISC OS 2 machines. The functionality of all these module
- versions have been incorporated into ROM under RISC OS 3.
-
- ----------------------------------------------------------------------------
- Q3) What's the minimum version of module X that my program needs? What
- features were introduced/what bugs were fixed in which versions?
-
- These details will come with the release notes accompanying the module
- and the particular program, if properly done, will inform you of which
- versions of the module you need as required.
-
- ----------------------------------------------------------------------------
- Q4) When using DOS discs I often find the last parts of files haven't been
- written correctly, what am I doing wrong?
-
- Under RISC OS 3 DOS, and indeed with any other ImageFS filing system,
- discs are treated as one large file and ADFS applies write-behind caching
- to nearly everything it does. (See the question on ADFSBuffers for more
- details about this.) This means while working on a DOS disc the entire disc
- is treated as one large open file.
-
- However as long as a file is held open the cache is not flushed out
- fully till the machine is explicitly told to do so. This means when working
- with non-ADFS format discs *always* dismount them before removing them from
- the drive. With ADFS format discs this is not so critical, as files aren't
- held open during most operations on them, but it is good to get into the
- habit of dismounting floppy discs.
-
- ----------------------------------------------------------------------------
- Q5) Why have there been no postings to comp.{binaries,sources}.acorn
- recently?
-
- The moderators run c.b.a and c.s.a in their spare time. They may not
- have any at the moment - they're studying hard at University. Please be
- aware the submissions address for the binaries and sources groups is
- cba@acorn.co.nz and *not* the moderators 'home' addresses - the distinction
- is important as they have to pay for incoming email at these addresses.
-
- ----------------------------------------------------------------------------
- Q6) What archives/FTP sites are available?
-
- See the regular (fortnightly) posting by Gerben Vos.
-
- ----------------------------------------------------------------------------
- Q7) How can I protect against viruses?
-
- Pineapple Software have produced a program called !Killer, which is the
- definitive means of checking for or killing viruses. See the next question.
-
- There are also a few PD programs around, but these tend to detect only
- a small subset of the viruses in circulation. !VKiller used to be OK,
- but it is no longer maintained, is now seriously out of date and fails to
- work under RISC OS 3. Out of the PD virus utilities the current best is Tor
- Houghton's Scanner. This detects most known virues and removes quite a few
- as well and serves as a good secondary defense if Killer is unavailable to
- you. Scanner should be available on various FTP/Email servers.
-
- ----------------------------------------------------------------------------
- Q8) Where can I obtain !Killer?
-
- It is now a commercial product and will be distributed by Pineapple
- Software. Who can be reached at:-
-
- 39 Brownlea Gardens, Seven Kings, Ilford, ESSEX IG3 9NL
- Tel. +44 (81) 599 1476 Fax +44 (81) 598 2343
- via email :-
- sales@pinesoft.demon.co.uk
- support@pinesoft.demon.co.uk
-
- Early versions (up to 1.26) are PD, but should not be used now as they are
- ineffective against the new crop of virus that have subsequently appeared
- since it's release.
-
- ----------------------------------------------------------------------------
- Q9) What is a VIDC enhancer? Will I need one for my new multisync monitor?
-
- A VIDC enhancer is basically a clock change for your VIDC. Most Arcs (bar
- the A540 and newer machines) have 24 MHz VIDC chips installed in them. A
- VIDC enhancer increases this to 36 MHz allowing much higher resolution
- screen modes to be displayed on your Arc. (800x600x16 or SVGA standard
- becomes available.) You do *not* need one to use a Multisync monitor - the
- standard VIDC handles that just fine. However having a VIDC enhancer is
- only really useful if you do have a Multi-sync monitor.
-
- ----------------------------------------------------------------------------
- Q10) What are the main new features of RISC OS 3?
-
- This information is now contained in my email server. If you wish to know
- the 'new' features of RO3 over RO2 then send a request to my email server,
- as detailed at the start of the FAQ, for the filename 'RO3diffs'.
-
- ----------------------------------------------------------------------------
- Q11) How do I enable solid drags in RISC OS 3?
-
- Solid drags are controlled by bit 1 in byte 28 of the CMOS RAM. Setting
- this bit enables solid drags on all solid drag 'aware' applications. However
- setting this bit using a *FX command from the command line is a foolish way
- to do it, as this will unset/set the other 7 bits in that byte which have
- meaning to FileSwitch and the Wimp. Accordingly the reccomended way to set
- this bit is using a program like this basic one enclosed below :-
-
- REM Toggle state of DragASprite bit in CMOS
-
- REM Read byte
- SYS "OS_Byte",161,&1C TO ,,byte%
- REM EOR byte with mask for bit 1
- byte% = byte% EOR 1<<1
- REM Write byte back again
- SYS "OS_Byte",162,&1C,byte%
- END
-
- Which safely sets bit 1 while preserving the settings of the other bits.
-
- (thanks go to Michael J Hardy for this one.)
- ----------------------------------------------------------------------------
- Q12) What kind of Acorn machines are there, and what are their
- specifications?
-
- The full list of Acorn made machines is somewhat lengthy now and are
- mostly no longer in manufacture. Accordingly this list distributed in the
- FAQ includes only Archimedes/ARM based machines, which are the currently
- manufactured by Acorn. A full list is maintained in my email server under
- the filename 'MachineLst'. This is, as far as I am aware, a complete list
- of all Acorn machines made with the possible exception of the latest
- machines for which I have yet to get the detailed specifications.
-
- A4 - Acorns first portable machine. The A4 is functionally an A5000 in
- portable form. Featuring power save modes, an LCD screen and software
- configuration of the power saving features it was released July 1992. It
- is called the A4 because it's footprint on a desk is apparently that of
- an A4 piece of paper. It is interesting to note that the A4 is *not* an
- A5000 squeezed into portable form but rather the A5000 is the A4 in
- desktop form, whereby the A5000 design was largely a spin off from the
- design of the A4.
- 2048k Memory
- Advanced Disc Filing System by default with High Density drives.
- ARM 3 processor. (24 MHz normally, 6 MHz in power save mode.)
- 12 MHz RAM. (3 MHz in power save mode.)
- 2048k OS in ROM.
- ~13.25 MIPS.
-
- A30x0 - Two models of this machine exist the A3010 and the A3020. Both are
- designed as low end 'family solution' machines. They are also among the
- first machines to feature the ARM250 processor offering improved
- performance over an ARM2 (but less than an ARM3) and are designed to
- supplement the A3000 machine as a low cost entry machine into the Acorn
- world. Its other main claim to fame is it is the first Archimedes series
- machine that features joystick ports (only in 3010 model, the 3020 has a
- network connector instead.). Launched August 27th 1992.
- 1024k Memory
- Advanced Disc Filing System by default with High Density drives.
- IDE 60 Mb Hard Drive (only in A3020 with HD option).
- ARM 250 processor
- 12 MHz RAM.
- 2048k OS in ROM.
- ~7.2 MIPS
-
- A4000 - This is a higher end more expandable version of the A30x0 series
- machines and is in a three box format similar to the A5000. It also is
- driven by an ARM 250 processor however it features over the A30x0
- machines optional Ethernet & Econet ports, a high density floppy drive
- and an 80Mb IDE drive by default. The aim of this machine is strongly
- towards the home office and more 'serious' applications than the A300x0
- series. Launched August 27th 1992.
- 2048k Memory
- Advanced Disc Filing System by default with High Density drives.
- IDE 80 Mb Hard Drive by default.
- ARM 250 processor
- 12 MHz RAM.
- 2048k OS in ROM.
- ~7.2 MIPS
-
- A5000 (alpha variant) - This is an improved variant on the A5000 featuring a
- considerably faster processor, 33 MHz, with the ability to have a
- similarly clocked FPA unit installed. It also features a considerably
- larger base hard drive size of 160 Mb on the 4 Mb model, the lower 2 Mb
- model still as an 80 Mb drive. Finally it has improved alterations to it
- allowing easy expansion of the machine to 8 Mb of memory by default. (IE
- without having to use third party solutions.) Released 10th September
- 1993.
- 2048k Memory
- Advanced Disc Filing System by default with High Density drives.
- IDE interface by default.
- ARM 3 processor. (33 MHz)
- 12 MHz RAM.
- 2048k OS in ROM.
- ~16.96 MIPS.
-
- Acorn RiscPC series
-
- This is the next generation and architecture of machines -
- superceeding, but compatible with, the Archimedes range of machines. 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 newer ARM6, and better,
- cell processors. This new range was launched on the 15th of April 1994
- with the RiscPC 600 series of machines.
-
- The new machines feature the processor card option, the concept of
- which was first shown in the A540 as well as a unique second processor
- slot allowing the machines to have two processors in the system, at once,
- of radically different types. Simply by slipping a 486 chip in, on an
- appropriate board of course, Intel based software can be run on the
- machine adjacent to native ARM programs. Both processors share the system
- resources and can be allocated memory and the like to use. Memory
- managment has been improved with memory paging always being done in 4Kb
- 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
- tranfers applications being boosted considerably. These machines are to
- be the ones to carry Acorn for the next three to six years and look set
- to do so nicely.
-
- RiscPC 600 2M HD210
- 2048Kb Memory. (No VRAM)
- Advanced Disc Filing System by default with a High Density drive.
- IDE interface by default. (210 Mb.)
- ARM 610 processor (30 MHz)
- 16 MHz RAM.
- 2048k OS in ROM.
- ~26 MIPS. (Arbitrary estimate.)
-
- RiscPC 600 5M HD210
- 4096Kb Memory. (1Mb of VRAM)
- Advanced Disc Filing System by default with a High Density drive.
- IDE interface by default. (210 Mb.)
- ARM 610 processor (30 MHz)
- 16 MHz RAM.
- 2048k OS in ROM.
- ~26 MIPS. (Arbitrary estimate.)
-
- RiscPC 600 9M HD420
- 8192Kb Memory. (1Mb of VRAM)
- Advanced Disc Filing System by default with a High Density drive.
- IDE interface by default. (420 Mb.)
- ARM 610 processor (30 MHz)
- 16 MHz RAM.
- 2048k OS in ROM.
- ~26 MIPS. (Arbitrary estimate.)
- ----------------------------------------------------------------------------
- Q13) What are the memory limits of the Acorn machines?
-
- For the most part the 8 bit machines were limited to a maximum of around
- 256k of memory. Although various expansion systems including second
- processors effectively meant the upper limit was about 1 Meg. (Although I
- have been told of a second processor with 4 Meg of memory in it. )
- For the early 32 bit machines *the* upper limit currently is 16 Meg of
- memory. Not all of the range of machines are capable of this however and
- the list looks something like this :-
-
- A3xx - 8 Megs maximum through third party, 1 Meg official limit.
- A4xx & A4xx/I - 8 Megs maximum through third party, 4 Megs official
- limit.
- A3000 - 4 Megs maximum through third party, 2 Megs official limit.
- A540 - 16 Megs maximum.
- A5000 - 8 Megs maximum through third party, 4 Megs official limit.
- A4 - 4 Megs official limit.
- A30x0 - 4 Megs official limit.
- A4000 - 4 Megs official limit.
- A5000 (alpha variant) - 8 Megs official limit.
-
- Newer RiscPC machines have an official upper limit of 256 Megs, plus 2
- Megs of VRAM, on all models. However this does require you using 128 Mbyte
- SIMMS which are currently not very common...
-
- ----------------------------------------------------------------------------
- Q14) What is a second processor and what second processors are there?
-
- A second processor was the generic name for a range of parasite
- processors that could be linked to Acorn's 8 bit machines via what was
- called the `Tube` interface. Basically the host machine became dedicated
- to handling the Input and Output while the second processor would do the
- higher level functions (like running your programs). The second processor
- ran asyncronously to the host processor allowing incredible increases in
- execution speed for programs. A wide range of processors were supported
- this way allowing Acorn's eight bit range of machines to remain viable
- and useful for much longer than their technology would suggest.
-
- The Second Processors that existed are :-
-
- Z80 second processor.
- 6 MHz RAM.
- 64k Memory.
- CP/M OS.
- External second processor for all eight bit machines.
-
- 6502 second processor.
- 3 MHz RAM.
- 64k Memory.
- Extended version of the BBC MOS.
- External processor for all eight bit machines.
-
- 32016 second processor.
- 6 MHz RAM.
- 256k-4096k Memory.
- Panos.
- External processor for all eight bit machines.
-
- ARM 2 second processor.
- 8 MHz RAM. (Guess...)
- 4096k Memory.
- Brazil OS.
- External processor for all eight bit machines.
-
- 6502 co-processor. (internal second processor).
- 4 MHz RAM.
- 64k Memory.
- Extended version of BBC MOS.
- Internal processor for Master 128 machines but could be fitted external to
- the other eight bit machines.
-
- 80186 co-processor.
- 10 MHz RAM.
- 512k Memory.
- DR-DOS+ with GEM.
- Internal processor for Master 128 machines but could be fitted external to
- the other eight bit machines.
-
- ----------------------------------------------------------------------------
- Q15) Are there any cards for IBM PC or compatable machines that Acorn have
- produced?
-
- Yes. Three cards in total :-
-
- Springboard.
- ARM 2 processor.
- 4096k Memory.
- 8 MHz RAM.
- Brazil OS.
-
- PC ARM development system.
- Precursor to Springboard. Hardware functionally identical.
-
- Ecolink.
- An econet link card for the PC.
-
- ----------------------------------------------------------------------------
- Q16) What configuration of serial cable should I use on my Arc for modem
- work?
-
- Here follows a diagram of the necessary connections for common terminal
- programs to work properly. They are as far as I know the informal standard
- agreed upon by commercial comms software developers for the Arc.
-
- Pins 1, 4, and 8 must be connected together inside the 9 pin plug. This
- is to avoid the well known serial port chip bugs. The modem's DCD (Data
- Carrier Detect) signal has been rerouted to the Arc's RI (Ring Indicator)
- most modems broadcast a software RING signal anyway, and even then it's not
- really necessary to detect it for the modem to answer the call.
-
- Arc (9 pin) Modem (25 pin)
- ----------- --------------
-
- +---1---DCD
- |
- | 2---RxD------------------------RxD----3
- |
- | 3---TxD------------------------TxD----2
- |
- +---4---DTR------------------------DTR---20
- |
- | 5---0v-------------------------SG-----7
- |
- | 6---DSR------------------------CTS----5
- |
- | 7---RTS------------------------RTS----4
- |
- +---8---CTS
-
- 9---RI-------------------------DCD----8
-
- Of course you can connect the Modem pin 20 to any one of pins 1, 4, or 8
- on the Archimedes plug, as they are all connected together anyway.
-
- Chocks Away Extra Missions (the flight simulator from 4th Dimension)
- suggests that the serial cable be wired as above except that pins 1-4-6 are
- connected together and the modem's CTS (pin 5) be connected to the Arc's pin
- 8 (ie the connections at pins 6 and 8 be swapped over at the Arc's end).
- This has been and it also seems to work fine.
-
- However newer Arc's like the A5000 have come out (and indeed the
- occasional A310) with a `corrected` serial port. This newer serial port
- operates as it should and is directly compatible with standard PC cables.
- Most comms software about at the moment does not take this in account and
- assumes that you have a cable patched in the manner described above. If you
- do not use such a patched cable on these `fixed` serial ports the software
- will generally fail to work.
-
- ----------------------------------------------------------------------------
- Q17) Can PC VGA Monitors be added to an Archimedes?
-
- It depends on what monitor you have, and what Archimedes you have. There
- are two main types of PC VGA monitors out there...
-
- 1) Fixed Frequency
- These monitors will only display video signals with certain
- line and refresh rates. They will typically only display
- CGA / EGA / VGA modes.
-
- 2) Multi Frequency
- These monitors will display any video signal within a certain
- range, typically 30-50Khz line rate and 50-80Hz refresh rate.
-
- Type 1 almost always require seperate syncs as the monitor uses the
- polarity of the syncs (mainly positive going negative or mainly negative
- going positive) to determine what the line and refresh rate should be.
-
- Type 2 vary. Some require seperate syncs (vertical and horizontal) and
- others will work with composite syncs (vertical and horizontal EOR
- together).
-
- As PC monitors typically start at a line rate of 30Khz compared to the TV
- broadcast modes (mode 12 etc.) that have a line rate of 15Khz, VIDC has to
- do more work to obtain a 30Khz line rate. This means that you computer will
- slow down silghtly if you use a 30Khz+ line rate monitor. If you have an ARM
- 3 fitted such slow downs will probably be negligable.
-
- Now, depending on what type of Archimedes you have depends on what type
- of monitor you can use.
-
- A540 / A5000 / A4 / A3010 / A3020 /A4000
- Has software control over the polarity of the syncs and what
- frequency VIDC is clocked at.
-
- The A540 with RISC OS 2 can only use modes 26-28 (640x480) and 31
- (800x600). However, by changing links and a *configure option, you can
- get the computer to generate seperate syncs with no problem.
-
- The other machines with RISC OS 3 can do even better. If you tell the
- computer that you have a VGA monitor it will re-map all of the
- 15Khz line rate modes up to 30KHz line rate. This means that
- you can play your games that require mode 12 / 13.
- However, as a PC monitor is designed to display 320 lines
- minimum then you will get a 'letterbox' effect as mode 12 has
- only 256 lines.
-
- All these machines have 24Mhz, 25.175Mhz and 36Mhz crystals to drive
- VIDC with. The 25.175Mhz crystal is needed to obtain the correct
- video rates for PC monitors displaying 640x480 screens. The 36Mhz
- crystal is used to obtain higher resolution modes, like 800x600x16
- colours.
-
- A3000
- This can generate seperate syncs but requires links to be set to
- determine the polarity. It has only a 24Mhz crystal and can
- therefore only drive 'forgiving' monitors correctly that don't
- mind the 640x480 video mode timings being slightly incorect.
-
- The links to change, to set the sync polarity, are as follows:
-
- Link 24: Change from SOUTH to NORTH
- Link 25: Change from OPEN to CLOSED
-
-
- In order to obtain proper timings, and software control of the
- sync polarity, you will need a VGA VIDC Enhancer for the A3000.
-
- A400 series.
- The situation gets more complex. Due to an 'error' in the PCB
- / circuit diagram, the A400 series cannot generate seperate
- syncs satisfactorly. The video signal loses the green component
- when seperate syncs is selected.
-
- As standard, there is no polarity control over the syncs. In
- common with the A3000, there is only a 24Mhz crystal.
-
- If the PC monitor can handle composite syncs then the monitor
- can be used in 640x480 mode only.
-
- A300 series.
- Most, if not all, of the A300 series had the circuit board
- hardwired into composite mode continously. There is only a 24Mhz
- crystal, and only composite PC VGA monitors can be used.
-
- RiscPC series.
- This has a *very* flexible VIDC in it and is quite capable of driving
- PC monitors with no trouble.
-
- However to connect an older machine (A3000,A300,400 series) to a VGA
- monitor, you will need a means of connecting the standard 15-pin VGA plug to
- the 9-pin socket in the computer. A number of companies sell 'converters',
- but all this boils down to is a lead with the following configuration :-
-
- .------------------------. VGA 15-pin socket
- \ 1 2 3 4 5 /
- \ 6 7 8 9 10 /
- \ 11 12 13 14 15 /
- '------------------'
-
- .------------------------. Arc 9-pin plug
- \ 1 2 3 4 5 /
- \ /
- \ 6 7 8 9 /
- '------------------'
-
- Signal VGA pin Arc pin
-
- Gnd 10 9
- Red 1 1
- Green 2 2
- Blue 3 3
- R gnd 6 6
- G gnd 7 7
- B gnd 8 8
- H 13 4
- V 14 5
-
- In conclusion, apart from the A5000 and newer machines, no computer as
- standard can drive either a fixed frequency or multi-frequency PC monitor in
- all of the Archimedes modes satisfactorily. However VIDC enhancer boards can
- be bought to upgrade an Archimedes to handle the needed timing and signals.
- ----------------------------------------------------------------------------
- Q18) What is ADFSBuffers and what is the best setting for it?
-
- ADFSBuffers are Read Ahead and Write Behind buffers for ADFS on your
- Archimedes. These are designed to improve the speed of filing operations by
- doing work at optimum times. There are some side effects of using them
- though. When active under RISC OS v2.00 and v2.01 discs *must* be
- dismounted before being removed from the floppy drive. Failure to do so
- results in the dreaded 'FileCore in use.' error. However if you are
- prepared to sacrifice the speed improvment they give configuring the
- buffers to 0 does remove this problem. (Or so I am informed.)
-
- Under RISC OS v3.00, as supplied with the early A5000 machines, these
- buffers generate a different problem and must *always* be configured off.
- Failure to do so results in spurious errors when using the Hard Drive on an
- early A5000. Symptoms include reformating of crucial sectors of the disc,
- disc address errors and general failure to save files to the drive. So when
- using an A5000 with RISC OS 3.00 remember to configure them to off!
-
- With RISC OS v3.10 all of the old problems have been cured with a new one
- introduced. Namely that if you have only a few ADFSBuffers configured and
- are accessing the floppy drive then your machine can occasionally lock up
- completely for you. It appears that any value of ADFSBuffers above 8 causes
- that problem to be largely alleviated (read it only occurs rarely at these
- settings). So under RISC OS 3.10 it is reccomended that you set your
- ADFSBuffers to 8+. There is a patch module available, called ADFSUtils,
- that does fix this problem - contact your local dealer for a copy of it.
-
- As for the optimum settings for ADFSBuffers, as far as I am aware no one
- has done any speed tests to see what is the best setting. Presumably though
- Acorn will have arranged for the system to start up (Well except for
- RO3.00...) in the optimum state for most uses. I would be interested in
- anyone who has done speed tests sending me the results of their
- investigations....
-
- ----------------------------------------------------------------------------
- Q19) What is the current File-type allocation ranges and why won't Acorn
- provide a full file-type list?
-
- Acorn have reallocated the File-type ranges for applications. The new
- ranges are :-
-
- Non-user area
-
- &E00-&FFF Acorn
- &B00-&DFF Commercial software
- &A00-&AFF Acornsoft, and other commercial software
- &400-&9FF Commercial Software
-
- User area
-
- &100-&3FF Non-commercial distributed software (ie PD)
- &000-&0FF User's personal usage (ie non-distributed)
-
- 75% of the user area is for PD/Shareware, with allocations co-ordinated by
- Acorn. If your software is going to be distributed, you should have an
- allocated filetype to avoid clashes.
-
- Acorn cannot publish it's master list of filetypes because, at any given
- time, it will contain allocations made for products which have not yet been
- announced. Therefore, Acorn would be in breach of confidence by doing so -
- and the editing overhead for producing a sanitised list is too great.
-
- ----------------------------------------------------------------------------
- Q20) My disc gives me a 'Broken Directory' or my Free Space Map is corrupt,
- what can I do?
-
- Unfortunately due to the highly complicated nature of the filing system
- data there is little that can be done easily. Your simplest and best way of
- correcting the problem is to backup as much software as you can and reformat
- your drive, restoring everything from those backups you make regularly...
- (What you don't back up your discs? :-) ) To do anything else requires a
- good knowledge of how the underlying structures work and is beyond the scope
- of this FAQ, although this detail is covered in the RISC OS 3 PRMs.
-
- ----------------------------------------------------------------------------
- Q21) My hard drive gives me disc errors when I use, what do the error
- numbers mean?
-
- The error numbers returned indicate the type of error encountered.
- Exactly why slightly more meaningful messages are not returned I am unsure.
- The error codes meanings are as follows :-
-
- ST506 error codes
-
- &01 ABT Command abort has been accepted
- &02 IVC Invalid command
- &03 PER Command parameter error
- &04 NIN Head positioning, disc access, or drive check before SPC has
- been issued
- &05 RTS TST command invalid after SPC
- &06 NUS USELD for a selected drive has not been returned
- &07 WFL Write fault has been detected on the ST506 interface
- &08 NRY Ready signal has been negated
- &09 NSC Seek completed (SCP) wasn't returned before a timeout
- &0A ISE SEK, or disc access command issued during seek
- &0B INC Next cylinder address greater than number of cylinders
- &0C ISR Invalid step rate: highest-speed seek specified in normal
- seek mode
- &0D SKE SEK or disc access command issued to drive with seek error
- &0E OVR Data overrun (memory slower than drive)
- &0F IPH Head address greater then number of heads
- &10 DEE Error Correction Code (ECC) detected an error
- &11 DCE CRC error in data area
- &12 ECR ECC corrected an error
- &13 DFE Fatal ECC error in data area
- &14 NHT In CMPD command data mismatched from host and disc
- &15 ICE CRC error in ID field (not generated for ST506)
- &16 TOV ID not found within timeout
- &17 NIA ID area started with an improper address mask
- &18 NDA Missing address mark
- &19 NWR Drive write protected
-
- IDE errors
-
- - As ST506, except:
-
- &02 IVC Command aborted by controller
- &07 WFL Write fault
- &08 NRY Drive not ready
- &09 NSC Track 0 not found
- &13 DFE Uncorrected data error
- &16 TOV Sector ID field not found
- &17 NIA Bad block mark detected
- &18 NDA No data address mark
- &20 No DRQ when expected
- &21 Drive busy when commanded
- &22 Drive busy on command completion
- &23 Controller did not respond within timeout
- &24 Unknown code in error register
-
- ----------------------------------------------------------------------------
- Q22) What does the power on self-test check and how does it signal errors
- back to you?
-
- The purple screen at power on indicates that the self-test has begun. A
- brief ROM, RAM, VIDC and IOC test is performed and then the screen colour
- changes to blue and a full memory test is performed, along with a second
- test of the VIDC and IOC. When the screen returns to purple, the machine is
- testing for an ARM3. At the end of this sequence the screen colour is set
- to green (for pass) or red (for fail). If the tests have all passed then
- the machine starts to boot and the RISC OS 3 welcome screen is displayed.
-
- If any test fails, the screen will remain red and the disc drive light
- will blink a fault code. A short flash is used to indicate a binary '0' and
- a long flash indicates a binary '1'. The bits are grouped into eight
- nybbles (blocks of four bits) with the most significant bit first.
-
- The lowest seven bits are a status word. The meaning of each bit is
- given below in hex :-
-
- 00000001 Self-test due to power on
- 00000002 Self-test due to interface hardware
- 00000004 Self-test due to test link
- 00000008 Long memory test performed
- 00000010 ARM 3 fitted
- 00000020 Long memory test disabled
- 00000040 PC-style IO world detected
-
- Bits 8-31 indicate the fault code and are described below. Not all the
- bits are used.
-
- 00000200 ROM failed checksum test
- 00000400 MEMC CAM mapping failed
- 00000800 MEMC protection failed
- 00004000 VIDC Virq (video interrupt) timing failed
- 00008000 VIDC Sirq (sound interrupt) timing failed
- 00020000 RAM control line failure
- 00040000 Long RAM test failure
-
- Some third party VIDC enhancers on older hardware trigger the self test to
- fail. If you are getting a failed self test with a VIDC enhancer, yet the
- machine is working fine, enter and run this BASIC program and then save your
- CMOS settings :-
-
- REM Toggle state of power on self test bit in CMOS
-
- REM Read byte
- SYS "OS_Byte",161,&BC TO ,,byte%
- REM EOR byte with mask for bit 1
- byte% = byte% EOR 1<<7
- REM Write byte back again
- SYS "OS_Byte",162,&BC,byte%
- END
-
- This modifies the self test to cope with the VIDC enhancer.
-
- ----------------------------------------------------------------------------
- Q23) Is there a Modula 2 compiler for the Arc?
-
- Currently, no. Acorn did have, in the early days of the experimental ARM
- work, an in house compiler. However this compiler was sufficiently unstable
- and buggy to be unreleasable as commercial product and was only used because
- in house support was available immediately to the users of the compiler.
- When Olivetti invested in Acorn this technology went to them so that Acorn
- no longer have even an in house Modula 2 compiler.
-
- However some companies have stated intentions to produce Modula 2
- compilers for the Arc. Whether these intentions become reality has yet to
- be seen.
- ----------------------------------------------------------------------------
- Q24) 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. Future 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 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.
- ----------------------------------------------------------------------------
- Q25) How compatible with other systems is an Archimedes?
-
- PC :- The Archimedes can handle DOS discs (720k; the A5000 and later
- models can also handle 1.44M floppies). In RO3, this is built in, under
- RO2 you have to use one of the (PD) utilities. There are two PC
- (software) emulators that can handle most PC software, three if you count
- the fact that Acorn's offering is split into two emulator programs. There
- are also PC cards, containing an 80x86 processor and other PC hardware,
- which uses the Archimedes' disc and video. All emulators are multitasking
- (and not PD). RiscPC machines, by adding a 486 processor card, can fully emulate a PC.
-
- Unix :- Unix software can be ported (and in fact many packages already
- have been) with the help of UnixLib, which is PD. Memory-hungry ports,
- such as gcc, can be run with the aid of !Virtual (also PD). Of course if
- your really desperate to run Unix software it might be advisable to buy
- RiscIx, the Acorn flavour of Unix.
-
- Mac :- Due to the pecularities of the double density Mac disc format it is
- difficult to read the Mac disc directly. However a company is releasing a
- filing system and drive combination to read Mac high density discs allowing
- transfers. Also Macs often can read PC format discs allowing transfers to
- occur using that medium. There is no Mac emulator available.
-
- Atari ST :- Like PC floppies, the Archimedes can read, write and format
- ST-format floppies. No emulator for the ST is known.
-
- Amiga :- The amiga uses an unusual disc format that is not easily read by
- other machines. Accordingly there is currently no Amiga format disc reader
- available. But Amiga's can read PC discs, so again transfers can occur via
- that medium. There is no Amiga emulator.
-
- Spectrum :- There are emulators around for this and Amstrad, the owners of
- the Sinclair copyright, have released permission for the ROM images, needed
- to run these emulators, to be copied and released with the emulators.
-
- Apple][ :- Again emulators are available for this. However they, like the
- Spectrum emulators, require a copy of the ROM image to work. The copyright of
- the ROM image for these machines, as far as I am aware, prevents them being
- distributed, so you have to source your own copy of it.
-
- ----------------------------------------------------------------------------
- Q26) What Acorn related companies are available on the net via email?
-
- There are quite a few companies now on the net and reachable via email
- with more joining as time passes. Here is the list of companies that have
- given permision to be entered here in the FAQ. If the email address is to a
- person rather than either an automated system or perhaps a group of people
- I have placed the name of the person in brackets after the email address
- description.
-
- Acorn Computers (Uk) :-
-
- customer.services@acorn.co.uk Enquiries and product information.
- RiscPC.techquery@acorn.co.uk RiscPC information.
- vhancock@acorn.co.uk Specials needs enquiries. (Vorn Hancock)
-
- Aleph One :-
-
- Sales@aleph1.co.uk Information about products and prices.
- Support@aleph1.co.uk After-sales support.
-
- Armstrong Walker Ltd :-
-
- Andy@armswalk.demon.co.uk Enquiries etc... (Andy Armstrong)
- Nigel@armswalk.demon.co.uk Enquiries etc... (Nigel Walker)
-
- Atomwide :-
-
- Sales@atomwide.co.uk Information about products and prices.
- Support@atomwide.co.uk After-sales support.
-
- Clares Micro Supplies :-
-
- DClare@Clares.demon.co.uk General enquiries. (Dave Clare)
- GOwen@Clares.demon.co.uk General enquiries. (Gareth Owen)
- DJackson@Clares.demon.co.uk Technical enquiries. (David Jackson)
- Sales@Calres.demon.co.uk Ordering and sales information.
-
- Colton Software :-
-
- info@colton.co.uk Automated reply, listing services available.
- sales@colton.co.uk general sales etc.
- support@colton.co.uk technical support on existing products.
-
- Computer Concepts :-
-
- info@cconcepts.co.uk Automated reply, giving information.
- sales@cconcepts.co.uk For credit card orders of products.
- support@cconcepts.co.uk Technical support for products.
-
- Comspec :-
-
- acorn_info@comrad.comspec.com Canadian Acorn dealer. Enquiries about Acorn
- hardware and products welcome including USA
- enquiries. (Domenic DeFrancesco)
-
- David Pilling Software :-
-
- david@pilling.demon.co.uk All enquiries to this address.
-
- Iota Software :-
-
- support@iota.co.uk Enquires & support for Iota products.
-
- Learning Curve Software Systems :-
-
- banks_p@kosmos.wcc.govt.nz Enquiries & technical support.
- (Philip R. Banks)
- howard_s@kosmos.wcc.govt.nz Enquiries. (Steve Howard)
- wright_j@kosmos.wcc.govt.nz Enquiries & technical support.
- (Julian Wright)
-
- SENLAC Computing :-
-
- sykesp@senlac.demon.co.uk Enquiries etc. (Peter R. Sykes)
-
- The Serial Port :-
-
- altman@cryton.demon.co.uk Software support.
- bob@cryton.demon.co.uk Retail enquiries.
- jim@cryton.demon.co.uk To reach Jim Nagel, author of the Acorn
- column in Computer Shopper magazine.
- pcats@cryton.demon.co.uk Hardware support
-
- Uniqueway :-
-
- info@uniqway.demon.co.uk General queries, product related or
- otherwise.
- support@uniqway.demon.co.uk Support for products. (Serial
- number should be quoted where
- relavent.)
- sales@uniqway.demon.co.uk For credit card orders.
-
- Warm Silence Software :-
-
- Robin.Watts@prg.ox.ac.uk Enquiries etc. (Robin Watts)
-
- Wyddfa Software
-
- gwilliams@cix.compulink.co.uk Enquiries etc. (Gwyn Williams)
-
- If you are a company and you would like to included in this list please send
- me an email, to the address specified at the bottom of the FAQ, detailing
- the email addresses and their general function. I will then include them
- into the FAQ.
- ----------------------------------------------------------------------------
- Q27) What versions of the processor are there and what are their
- capabilities?
-
- There are currently four commercially available ARM processors with up
- to seven possibly being available soon. I will seperate the processors into
- two sections, those currently available and those soon to be available.
-
- Currently available processors
- ------------------------------
-
- ARM1 This was the very first ARM processor and was very close in
- capabilities to the ARM2. As far as I am aware this processor was never
- commercially used in any machines, but was mostly a prototype chip.
- Indeed I am given to understand there may have been only a hundred of
- these chips ever made. The exact, major, differences between an ARM2 and
- an ARM1 are :-
-
- -No banked R8 and R9 in FIQ mode.
- -No multiply instruction.
- -LDR/STR instructions with register specified shift amounts. (Withdrawn
- from the ARM2.)
- -No co-processor interface or co-processor instructions.
-
- ARM2 The ARM2 chip, and processor cell, features 27 registers of which 16
- are accesable at any one time. Four processor modes are available -
-
- USR : user mode
- IRQ : interupt mode ( with a private copy of R13 and R14.)
- FIQ : fast interupt mode ( private copies of R8 to R14.)
- SVC : supervisor mode. (private copies of R13 and R14.)
-
- Only non USR mode code may change the processor mode providing hardware
- security if the hardware and physical memory is only accesable from
- privileged, ie non USR mode, code. Due to the top eight bits of the
- program counter being used to hold the processor status flags this
- chip was restricted to addressing 26 bits of memory, or a 64 Megabyte
- address space.
-
- The ARM2 chip was the first incarnation of this cell and was
- clocked at 8 MHz giving an average performance of 4-4.7 MIPS. The
- second incarnation of the chip was as the ARM250 which was a 12MHz
- variant of the ARM2 cell and had the IOC1, VIDC1a and MEMC1 chips all
- integrated into the one chip. The ARM250 delivered about 7 MIPS
- performance.
-
- Rumours abound of 20 MHz ARM2 chips having been produced and used.
- Currently no information about this has been seen by the FAQ
- maintainer.
-
- ARM3 This is an uprated ARM2 cell, well to be more accurate it as an ARM2
- core macrocell with a cache and dedicated coprocessor interface added.
- The register set was unchanged and no new processor modes were added.
- What was new, in the ARM3 chip produced, was the addition of an on chip
- cache (4Kbyte, 64 way set associative, random replacement, 4 word lines,
- write through, mixed data and instructions.) and much faster clock
- speeds. Also new were adjustments to the co-processor interface on the
- chip including defining co-processor fifteen to be cache control and chip
- identification.
-
- Finally one new instruction was added, the SWP instruction. A
- monotonic register to memory swap command useful for multi-processor
- arrays.
-
- Several speeds of ARM3 chips were produced. Initially 26 MHz
- varieties were released with the A540 machines, then 25 MHz versions
- were used in the A5000 and 24 MHz ones in the A4. Finally a 33MHz
- version was produced and used in the alpha varient of the A5000.
-
- However this is merely the bulk produced versions. Many third
- parties have taken lower rated ARM3 chips and tested them at higher
- speeds, sorting the ARM3s into classes of chips that could work at
- varying speeds. Consequently there are hordes of ARM3 chips out there
- running at varying speeds. The highest I have heard of is about 37 MHz.
-
- A 24 MHz ARM3 using a 12MHz main memory will produce an average
- speed of execution of 13.26 MIPS. At 33 MHz 17.96 MIPS is delivered.
-
- ARM4 & ARM5. It is not known what the capabilities of these cells are, or
- even if they exist. It is assumed by the FAQ maintainer that these
- cells remained in house designs and were inbetween stages between the
- ARM3 and the ARM6 cell.
-
- ARM6 This processor cell is the first of the commercially available ARMs
- to have a full 32bit addressing capability. Additionally the processor
- now has 31 registers in it along with six new processor modes :-
-
- User32 32 bit USR mode.
- Supervisor32 32 bit SVC mode. (private SPSR register)
- IRQ32 32 bit IRQ mode. (private SPSR register)
- FIQ32 32 bit FIQ mode. (private SPSR register)
- Abort32 Memory fetch abort more. (private SPSR register)
- Undefined32 Undefined instruction mode. (private SPSR register)
-
- The SPSR register is a Saved Processor Status Register and holds a
- copy of the CPSR (Current Processor Status Register) when the new mode
- is entered. The addition of the Abort32 mode and this change, although
- the CPSR/SPSR is really a corollary of the change to 32bits, allows the
- ARM6 cell to easily handle virtual memory without the contortions you
- had to go through on earlier cell ARM chips.
-
- Two new instructions for reading and writing the CPSR and SPSR
- registers were added. The program counter is now fully 32 bit with the
- CPSR being hardware shifted into position when the PC is read in 26
- bit modes. (for backwards compatibality.) The ARM6 cell is fully
- binary compatible, in the 26 bit modes, with the earlier ARM cell's code.
- The chip is fully static, the clock can slowed to any speed and the
- processor will maintain state. Finally the cell can work in either
- big-endian or little endian operation can be hardware switched between
- the two modes. Total register count in the ARM6 cell (not chip) is
- 36,000 transitors.
-
- Several versions of the ARM6 cell have been produced. The ARM61 is a
- hardwired version of the ARM6 cell in ARM2/3 compatibility mode. This
- chip cannot enter the 32bit address/processor modes. The ARM600 range
- of chips is an ARM6 cell with an inbuilt MMU, on chip cache similar
- to the ARM3 chip's, an eight deep write back buffer with two
- independant addresses and a total transitor count of 360,000. The cache
- has had performance tweaks, is now controlled by the MMU and has been
- adjusted for 32 bit addressing. Two ARM610 chip speeds have been
- produced. One at 20 MHz delivering 17 MIPS and one at 30 MHz delivering
- 26 MIPS performance.
-
- Also available are the ARM60 (an ARM 6 cell as a chip, without
- anything else.), ARM650 (An ARM6 with some RAM & peripheral controllers.
- Designed for embedded control systems.), ARM6l (lower power ARM6 cell)
- and the ARM60l (lower power version of the ARM 6 cell as a chip.).
-
- ARM7 The ARM7 cell is functionally identical to the ARM6 cell in
- capabilities but may be clocked faster than the ARM6. A variant of the
- ARM7 cell offers an improved hardware multiply, suitable for DSP work.
-
- Most of what is new in the ARM7 cell is internal changes on timings
- for various signals. The ARM700 chip has a larger on chip cache (8kb,
- and radically altered for power efficiency) to the ARM600, improving
- cache hit rates. It also has twice the number of translation lookaside
- entries in the MMU and twice the number of address on the write buffer.
- (Presumably now four address can be written too before the buffer
- stalls.) Judging by dhrystone ratings for the ARM700 it is expected that
- this chip will deliver, at 33 MHz about 32 MIPS performance. But this
- speculation on the FAQ maintainers part.
-
- ARM7 series devices are ARM7 (chip cell core.), ARM7D (the chip core
- with debugging support.), ARM7DM ( an ARM7D with an enhanced multiply.),
- ARM7DMI (an ARM7DM with ICEbreaker (tm). ICEbreaker is on chip support
- for In-Circuit-Emulation.), ARM70DM (ARM7DMI as a chip.) and the ARM700
- (ARM7 + MMU + cache + Writeback Buffer.).
-
- Future processors.
- ------------------
-
- ARM8 This is expected to be the super-scalar version of the ARM
- processor. Figures stated on the net would seem to imply dhrystone
- ratings in the 100-120k range. This implies a performance in the
- neighbourhood of 50 MIPS, but again this purely speculation. No
- details are available, or more accurately have been seen by the FAQ
- maintainer, as to what is new in this chip cell.
-
- Apparently the official position is that the ARM8 will be at least as
- twice as fast as the ARM7 cell, when made with the same fabrication
- process.
-
- AMULET1 This is an asynchronous version of the ARM6 cell processor.
- Performance levels are similar to the ARM6 but with the AMULET1
- showing a promising future in the area of power saving. No commercial
- versions of this processor currently exist and it is likely that only
- the AMULET2 cell will be commercially available.
- ----------------------------------------------------------------------------
- Q28) What are the graphics capabilities of the Acorn machines?
-
- All the Acorn machines are highly upgradable 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. Resoultions
- possible :-
-
- X res. Y res. Colours
- 640 256 2
- 320 256 2
- 320 256 4
- 160 256 4
- 160 256 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
- 320 256 2
- 640 256 2
- 640 480 2
- 640 512 2
- 1152 896 2
- 160 256 4
- 320 256 4
- 640 250 4
- 640 256 4
- 640 480 4
- 640 512 4
- 160 256 16
- 320 256 16
- 640 250 16
- 640 256 16
- 640 480 16
- 640 512 16
- 1056 250 16
- 1056 256 16
- 160 256 256
- 320 256 256
- 640 256 256
- 640 480 256
- 640 512 256
- 1056 256 256
-
- 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, A500,
- 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 provdied
- true PC VGA style compatibility for monitors instead of a 24 MHz
- 'faked' version which sometimes caused problems with intollerant VGA
- monitors.
-
- X res. Y res. Colours
- 320 256 2
- 640 200 2
- 640 256 2
- 640 480 2
- 640 352 2
- 640 512 2
- 768 288 2
- 800 600 2
- 896 352 2
- 1152 896 2
- 160 256 4
- 320 256 4
- 640 200 4
- 640 250 4
- 640 256 4
- 640 352 4
- 640 480 4
- 640 512 4
- 768 288 4
- 800 600 4
- 896 352 4
- 160 256 16
- 320 256 16
- 640 200 16
- 640 250 16
- 640 256 16
- 640 352 16
- 640 480 16
- 640 512 16
- 768 288 16
- 800 600 16
- 896 352 16
- 1056 250 16
- 1056 256 16
- 160 256 256
- 320 256 256
- 640 200 256
- 640 256 256
- 640 352 256
- 640 480 256
- 640 512 256
- 768 288 256
- 896 352 256
- 1056 256 256
-
- Because the display hardware was essentially the same as the 8MHz
- machines' the palette handling wa identical.
-
- Risc PC machines. This covers all Risc PC in the Risc PC 600 series. Here
- the newer VIDC20 chip has been used and the display capabilities are
- somewhat extended. Namely :-
-
- X res. Y res. Colours
- 320 256 2
- 640 200 2
- 640 256 2
- 640 480 2
- 640 352 2
- 640 512 2
- 768 288 2
- 800 600 2
- 896 352 2
- 1152 896 2
- 160 256 4
- 320 256 4
- 640 200 4
- 640 250 4
- 640 256 4
- 640 352 4
- 640 480 4
- 640 512 4
- 768 288 4
- 800 600 4
- 896 352 4
- 1280 1024 4
- 160 256 16
- 320 256 16
- 640 200 16
- 640 250 16
- 640 256 16
- 640 352 16
- 640 480 16
- 640 512 16
- 768 288 16
- 800 600 16
- 896 352 16
- 1024 768 16
- 1056 250 16
- 1056 256 16
- 1280 1024 16 1 MB of VRAM
- 160 256 256
- 320 256 256
- 640 200 256
- 640 256 256
- 640 352 256
- 640 480 256
- 640 512 256
- 768 288 256
- 800 600 256
- 896 352 256
- 1024 768 256 1 Mb of VRAM
- 1056 256 256
- 1280 1024 256 2 Mb of VRAM
- 1600 1200 256 2 Mb of VRAM
- 800 600 32,000 1 Mb of VRAM
- 1024 768 32,000 2 Mb of VRAM
- 800 600 16,000,000 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.
-
- 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 mappings 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.
-
- 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.
- ----------------------------------------------------------------------------
- Q29) What are the differences between RISC OS 3.5 and RISC OS 3.11 & 3.10?
-
- There are alot of behind the scenes differences but the most obvious changes are :-
-
- -The system font has been replaced by an outline font.
-
- -The Filer uses solid drag icons, including a 'package' icon for multiple
- file drags.
-
- -Error dialogue boxes can now have a button for requesting interactive help
- on the error.
-
- -Windows can have textured backgrounds by default. (This feature can be
- used indepndantly of the application supporting it.)
-
- -Applications can have up to 28Mbs of memory apeice, if available.
-
- -The Palette utility has been replaced by the Display Manager, offering an
- alternative method of choosing screen modes from the older mode number
- method.
-
- -The Task Manager allocates memory via logarithmicly scaled slider bars.
-
- -Rogue tasks can be stopped, or killed, by pressing Alt-Break.
-
- -The CMOS & hard drive can be protected from alteration.
-
- Also, due to the new hardware, there are alot of behind the scenes
- extentsions to the OS including the provision of new dynamic areas, extended
- podule support, hard drive locking and a wealth of other features.
- ----------------------------------------------------------------------------
- Thanks go to all the people who have contributed corrections and
- additions to the list. Without this help this list would be a hell of alot
- buggier (spot the programmer... :-) ) than it is...
- ----------------------------------------------------------------------------
- All additions, corrections & suggestions for the FAQ List should be sent to
- -=> banks_p@kosmos.wcc.govt.nz <=-
- Being the maintainer of this FAQ I reserve the right to be wrong, incorrect,
- slow, out of date and generally how I please with the FAQ List.
-