From: banksie@khantazi.welly.gen.nz (Philip R. Banks)
Subject: Comp.Sys.Acorn FAQ List Posting (Automatic)
Followup-To: comp.sys.acorn
Keywords: Frequent Questions Answers
Reply-To: banks_p@kosmos.wcc.govt.nz
Organization: My Arc.
Date: Thu, 17 Dec 1992 14:49:17 GMT

Archive-name: acorn/faq

   Comp.Sys.Acorn FAQ List. Last alterations 10/Dec/1992
   -----------------------------------------------------

-------------------------------------------------------------------------------
Recent alterations :-
        -Minor fix to the Master 512 co-processor entry.
        -Question 20 added.
-------------------------------------------------------------------------------

   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) I have had problems with my printer. It's a dot matrix printer, when
      printing graphics or a document, it sometimes mangles a line of
      output, usually printing a $ sign, too.

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 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?

----------------------------------------------------------------------------
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. Ideally your local 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.)

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

----------------------------------------------------------------------------
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.

----------------------------------------------------------------------------
Q4) I have had problems with my printer. It's a dot matrix printer, when
printing graphics or a document, it sometimes mangles a line of output,
usually printing a $ sign, too.

Get your dealer to carry out Field Change Order XXX (which corrects the
problem). Or if you are competant enough do it yourself like this :-

1)  Remove the circuit board from the computer.

2)  Locate and identify resistor R24. Cut the leg of R24 closest to IC9, and
carefully move the free end of R24 away from the adjacent resistor. Secure R24
to the PCB with adhesive (for example Loctite TAC PAC), leaving the free end of
R24 available for soldering.

3)  Prepare new IC (74HC14) by:
          Removing pins 5,6,8,9,10,11,12 and 13
          Lift pins 1 and 4 ready to solder leads
          Lift pins 2 and 3, and solder them together

4)  Position new IC onto IC15 piggyback fashion so that pin 1 of the new IC is
directly above pin 1 of IC15. Solder pins 7 and 14 of the new IC to pins 7 and
14 of IC15.

5)  Solder thin insulated lead from pin 1 of the new IC to the free end of R24.
Solder a second insulated lead from pin 4 of the new IC to the vacated pad of
R24. Keep these leads as short as possible, and secure them to the PCB with
adhesive.

6)  Reassemble the computer and check operation of the printer port.

The 74HC14 IC is widely available.........(Acorns part No)....

Please note that it is particularly important that a profile of this
modification is kept as low as possible, to ensure that there is no fouling of
the modification on any podules that may be fitted to the computer.

Be warned that modifying your Archimedes invalidates the warranty on it and
should preferrably be carried out by an Acorn sanctioned technician.
----------------------------------------------------------------------------
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.

----------------------------------------------------------------------------
Q6) What archives/FTP sites are available?

See the regular (fortnightly) posting by Gerben Vos.

----------------------------------------------------------------------------
Q7) How can I protect against viruses?

Acorn 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

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 A5000 and the A540) 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?

   Most of the features of Risc OS 3 are behind the scenes stuff for
programmers, improving the program to OS interfaces. However there are quite
a few improvements to the user interface :-

        * Multitasking Filer operations.
          Copying, moving, and deleting files no longer takes control away
          from the user. The user can now go on using the computer
          while the filing operations are taking place.

        * Multitasking Format/Verify/Backup
          These operations, which used to take a long time on RISC OS 2.00
          are now performed in the background, enabling the user to continue
          and make other use of the computer while they are taking place.

        * Multitasking Free space display.
          The free space display for floppy and hard discs now gives a
          continuous view of the free space on the disc while the computer
          is being used.

        * Additional Filer operations.
          It is now possible to search for a file, set a file's type, and
          date stamp a file from the Filer menu.

        * Applications in ROM.
          Improved versions of many of the main applications that were
          provided on disc with RISC OS 2.00 are now resident in ROM.
          These applications can be accessed using the Apps icon on the left
          hand side of the icon bar.

        * Automatic starting of applications
          Any of the ROM applications can be set to start automatically when
          the computer is powered on.

        * Fonts in ROM
          Many of the fonts that were provided on disc with RISC OS 2.00 are
          now resident in the RISC OS 3 ROM.

        * No limit on number of open windows.
          There is no longer a limit on the number of windows that can be
          opened at once.

        * Ability to move windows off screen.
          Windows can now be moved partly off screen, to increase the usable
          screen space.

        * Desktop saving
          Ability to save the computer's state and restore it when the user
          next uses the machine.

        * Computer shutdown.
          An option is provided to safely close the computer down, ready for
          turning it off.

        * Pinboard.
          Frequently used files can now be held on the desktop background
          for easy access.
          A background picture can also be displayed on the desktop.

        * Iconized windows.
          An open window can be shrunk to an icon, and stored on the
          desktop background. It can later be restored to its previous size
          be clicking on the icon. This helps reduce the space used by
          windows when they are not being actively used.

        * Improved printer support.
          A new printer driver manager !Printers is provided with RISC OS 3
          which makes printing easier.
          RISC OS 3 makes it possible to have more than one printer
          connected to your computer at the same time, with all connected
          printers accessible from the desktop.

        * Ability to read MS DOS(tm) format discs.
          It is now possible to use discs that were created on a computer
          running MS DOS(tm) from RISC OS 3 to move data between the Acorn
          range of computers and any computer running MS DOS(tm).

        * Support for new A5000 high density floppy formats.
          It is now possible to use 1.6MB floppy discs on computers which
          support it such as the A5000.

        * Broadcast Loader.
          RISC OS 3 includes support for broadcast loading on Econet
          networks. This greatly improves the speed at which applications
          and data are loaded on multiple computers on the network.

        * ARM3 support.
          RISC OS 3 includes built in support for the ARM3 processor that is
          used on the A540,R260 and A5000 computers.

        * Ability to use named hard discs.
          Hard discs which are given a name now have their name displayed
          under their icon on the icon bar, eliminating the need to refer to
          the same disc by both its name and number.

        * Grouping of icon bar icons.
          On RISC OS 3 icons of the same type will appear on the icon bar in
          a group, regardless of the order they were added to the icon bar.
          For instance all hard disc icons will appear in a group, and so
          will all the fileserver icons. This makes finding the icon you
          want easier.

        * Enhanced interactive help.
          When running !Help, help can now be provided on menu items as well
          as on icons and windows, making it easier to learn how to use new
          application software.

        * Extension modules in ROM.
          All of the standard extension modules for RISC OS 2.00 such as
          ColourTrans, the floating point emulator, the outline font
          manager and the shared C library are now in the RISC OS 3 ROM
          leaving more memory for application software.

        * Up to 128 tasks.
          RISC OS 3 can support up to 128 tasks running together in the
          computer as opposed to the 32 allowed by RISC OS 2.00.

        * New hot keys.
          New hot keys are provided to open a task window, move the icon bar
          to the front, and start a shutdown.

        * Screen blanker.
          A screen blanker is included in the RISC OS 3 ROM to help preserve
          the monitor screen.

(lifted from Ran Mokady's RO3 Q&A posting. Thanks Ran....)
----------------------------------------------------------------------------
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 Micheal 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 current
commonly ecountered Acorn machines. 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.

A500 - never sold commercially this machine will be a little hard to find.
   It was the development machine for the A300/A400 series of machines. One
   of its major `idiosyncracies` is that it uses the older VIDC1 chip which
   used different logic for sound output than all commercialy released Arcs
   and thus most sound modules sound very odd on it...
   4096k Memory.
   Advanced Disc Filing System by default.
   ARM 2 processor.
   8 MHz RAM. (Ocassional unit with 12MHz RAM.)
   512k OS in ROM.
   ~4 MIPS

A3xx - the first of the Archimedes range of computers it was powered by a
   custom designed chip set based around the ARM a 32 bit RISC chip. The
   range started with half a Meg of memory up ran up to 1 Meg of memory.
   They came out with the Arthur Operating system that while it was more
   advanced than the 8 bit machines OS's it was not an OS doing justice to
   the hardware it was running on. Released around late 1987 they heralded
   the start of new shift in Acorn machines away from their previous 6502
   only base.

   A305
   512k Memory.
   Advanced Disc Filing System by default.
   ARM 2 processor.
   8 MHz RAM.
   512k OS in ROM.
   ~4 MIPS

   A310
   1024k Memory
   Advanced Disc Filing System by default.
   ARM 2 processor.
   8 MHz RAM.
   512k OS in ROM.
   ~4 MIPS

A4xx - released at the same time as the 300 series of machines the 400
   series features an in built st506 hard drive controller and some models
   came equiped with hard drives built in as standard and the series also ,
   by default, was capable of handling 4 expansion cards including a
   co-processor card unlike the 300 series.

   A410
   1024k Memory
   Advanced Disc Filing System by default.
   St506 Hard Drive interface by default.
   ARM 2 processor.
   8 MHz RAM.
   512k OS in ROM.
   ~4 MIPS

   A420
   2048k Memory
   Advanced Disc Filing System by default.
   St506 Hard Drive interface by default.
   ARM 2 processor.
   8 MHz RAM.
   512k OS in ROM.
   ~4 MIPS

   A440
   4096k Memory
   Advanced Disc Filing System by default.
   St506 Hard Drive interface by default with Hard Drive. (43 Meg)
   ARM 2 processor.
   8 MHz RAM.
   512k OS in ROM.
   ~4 MIPS

A680 - development machine for RISCiX. This is another development machine
   and again was never sold commercialy. Thus it is somewhat rare. It was
   different from most Arcs in the respect that it does not have RiscOS in
   ROM at all and can only use high resolution monochrome monitor for
   display. It came with a 67 Meg SCSI drive by default.
   8192k Memory.
   SCSI by default. (67 Meg drive)
   ARM 2 processor.
   8 MHz RAM.
   Unknown. (Runs RISCiX...)
   ~4 MIPS

R140 - Acorn's entry machine into the Unix market, it suffered problems due
   to the Archimedes chip set not being optimal for running Unix on.
   Functionally identical to an A440 machine it had 4 Meg of memory and was
   provided with an 52 Meg st506 drive with RISCiX (Acorns brand of Unix) on
   it.
   4096k Memory
   Advanced Disc Filing System by default.
   St506 Hard Drive interface by default with Hard Drive. (53 Meg)
   ARM 2 processor.
   8 MHz RAM.
   512k OS in ROM. RISCiX OS supplied on Hard Drive.
   ~4 MIPS

A3000 - this is the low end Arc. It was the first machine to be released
   with the newer and faster MEMC1a built in as standard as well as the
   newer Risc OS by default. Designed to be a cost effective cheap Arc it
   features only one full expansion port with a single internal `mini`
   expansion card slot limiting expansion somewhat. It also came by default
   without a serial port. This machine has proved very popular with schools
   as a cheap entry into the new Archimedes machines.
   1024k Memory
   Advanced Disc Filing System by default.
   ARM 2 processor.
   8 MHz RAM.
   512k OS in ROM.
   ~4.7 MIPS

A4xx/I - this series was functionally identical to the 400 series but
   featured a newer memory controller the MEMC1a that gave it a slightly
   faster speed. It also came with a 53 Megabyte hard drive in the higher
   end models that came with HD's rather than the 400 series's 20 Meg one.

   A420/I
   2048k Memory
   Advanced Disc Filing System by default.
   St506 Hard Drive interface by default.
   ARM 2 processor.
   8 MHz RAM.
   512k OS in ROM.
   ~4.7 MIPS

   A440/I
   4096k Memory
   Advanced Disc Filing System by default.
   St506 Hard Drive interface by default with Hard Drive. (53 Meg)
   ARM 2 processor.
   8 MHz RAM.
   512k OS in ROM.
   ~4.7 MIPS

A540 - the current high end Archimedes machine this machine comes with 4 Meg
   of memory by default and an ARM 3 processor running at 26 MHz. It comes
   with a 100 Meg SCSI drive by default and a slightly newer version of
   Risc OS updated to cope with up to 16 Meg of memory and features for
   handling the ARM 3 processor.
   4096k Memory
   Advanced Disc Filing System by default.
   SCSI Hard Drive interface by default with Hard Drive. (100 Meg)
   ARM 3 processor.
   12 MHz RAM.
   512k OS in ROM.
   ~13.5 MIPS (I am guessing here...)

R260 - functionally identical to the A540 the R260 comes with Unix (well
   RISCiX ) by default and due to the increased power of the hardware runs
   it much better.
   8192k Memory
   Advanced Disc Filing System by default.
   SCSI Hard Drive interface by default with Hard Drive. (100 Meg)
   ARM 3 processor.
   12 MHz RAM.
   512k OS in ROM. RISCiX OS supplied on Hard Drive.
   ~13.5 MIPS

R225 - A diskless version of the R260 it was designed to be a cheap
   networked Unix station. Released at the same time as the R260.
   4096k Memory
   Advanced Disc Filing System by default.
   ARM 3 processor.
   12 MHz RAM.
   512k OS in ROM. RISCiX OS booted off from Network connections.
   ~13.5 MIPS

A5000 - the A5000 is the first machine to feature high density (quad - 1.6 Meg
   formated) drives by default as well as the latest version of Risc OS -
   version 3. It also features an inbuilt IDE drive on it's higher end model.
   Released late 1991.
   1024k Memory
   Advanced Disc Filing System by default with High Density drives.
   IDE interface by default.
   ARM 3 processor
   12 MHz RAM.
   2048k OS in ROM.
   ~13.5 MIPS.

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.
   2048k Memory
   Advanced Disc Filing System by default with High Density drives.
   ARM 3 processor (6 MHz in power save mode.)
   12 MHz RAM. (3 MHz in power save mode.)
   2048k OS in ROM.
   ~13.5 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
   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.
   Launched August 27th 1992.
   1024k Memory
   Advanced Disc Filing System by default with High Density drives.
   IDE 60 Mb Hard Drive (only in A3020).
   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 that 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

----------------------------------------------------------------------------
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.
   For the 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 - 2 Megs official limit.
   A4000 - 4 Megs official limit.

----------------------------------------------------------------------------
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.

16032 second processor.
Unknown.
256k-4096k Memory.
Unknown. (Panos at a guess)
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 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, an 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) Mutil 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
      Has software control over the polarity of the syncs and what
      frequency VIDC is clocked at.

      The A540 with RiscOS 2 can only use modes 26-28 (640x480)
      [I can't rember if an A540 has a mode 31, help?]. However, by
      changing links and a *configure option, you can get the computer
      to generate seperate syncs with no problem.

      The A5000 with RiscOS 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.

      Both the A540 / A5000 have a 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.

      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.

Conclusion:
  Apart from the A5000, 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.
----------------------------------------------------------------------------
Q19) 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 A5000 machine, 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 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 remember to
configure them to off!

   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 the A5000...) 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.

----------------------------------------------------------------------------
 Thanks go to Julian Wright for his diagrams and comments on the serial
port. Also 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 a student I reserve the right to be wrong, incorrect, slow, out of
          date and generally how I please with the FAQList.