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|FPPh
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PrQP
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PrQP
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vV2ui6`#6^#vVFuN6p#6n#vvFt  ~9&X&&e%PFPWƋFv 2PP ]	9&X& & V\2PP ]	
:&u9&X& & ˎ9&X&&k%PFPVǋFvW	3^_]UWVF ǆP  Ɔ{ ǆ8o%:ǆ<w%>ǆ@~%BǆD%FǆH%J+NL9&
&
vx~prt89
+&G&n9&9ptH9&9vt= PP9&6&6` %P9&6&6Z T 
%P|	T:& P 	FVpP 	FV+FF{{<vv~ uZ6`#6^#%P~V P~V"P~VJ]	- 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.

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

      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 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 byk 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. 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.
----------------------------------------------------------------------------
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 lthough 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 :-

   06 unit select signal has not been returned by drive
   07 write fault signal from drive
   08 drive not ready
   09 seek complete has not been returned
   10 data error has been detected by ECC (Error Correction Code)
   13 a fatal ECC error has occurred in DATA area
   16 sector ID has not been found
   17 an ID area that begins with an improper address mark has been detected
   18 the address mark in DATA has not been detected

----------------------------------------------------------------------------
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 this command and save your CMOS settings :-

*FX 162,&BC,&80

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.

   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).

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 seem to be a couple of Spectrum emulators around, but
(according to rumour) they can't be distributed legally because they
require the contents of the ROMs, and Sinclair still holds the
copyright.

----------------------------------------------------------------------------
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) :-

   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.

Atomwide :-

   Sales@atomwide.co.uk  Information about products and prices.
   Support@atomwide.co.uk After-sales support.

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)

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