Comp.Sys.Acorn FAQ List Posting (Part 1/2)
Philip R. Banks
Frequency: bi-weekly
Comp.Sys.Acorn FAQ List. Last alterations 8/Jun/1995
====================================================
----------------------------------------------------------------------------
Recent alterations :-
Question 1.1 added.
Section 1 subsequently re-arranged.
The FAQ now features an expires header. I am working on the superceeds
header.
Question 1.2 updated.
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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 :-
And I'll try to add them as soon as possible....
This FAQ is posted bi-weekly to comp.sys.acorn, comp.sys.acorn.announce
and news.answers. 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-...@rtfm.mit.edu. No subject is needed and the body should be :-
send /pub/usenet/news.answers/acorn/faq
Also the FAQ itself and sub-sections of it are stored in an email server
I personally run. See section 7.4 for further details on how to access this
email server.
Lastly this list is copyright to Philip R. Banks but permission is
granted for free distribution of the entire list or quoted segments of it.
If you wish to include segments of the list into other documents then proper
attribution must be performed and if you wish to include and part of the
list, or the list in full, in any commercial product then express permission
must be obtained from myself.
Index of Questions.
===================
The questions have been catagorised loosely into related sections, in an
effort to make finding the desired information simpler and quicker.
Section 1: Acorn Hardware and Operating Systems.
------------------------------------------------
1.1) What is an Acorn machine?
1.2) What kind of Acorn machines are there?
1.3) What versions of the processor are there and what are their
capabilities?
1.4) What are the main new features of RISC OS 3?
1.5) What are the differences between RISC OS 3.5 and RISC OS 3.11 & 3.10?
1.6) What are the graphics capabilities of the Acorn machines?
1.7) Is Virtual Memory possible under RISC OS?
1.8) What is the current status of Linux for Acorn machines?
Section 2: Upgrades and Expansion.
----------------------------------
2.1) What are the memory limits of the various Acorn machines?
2.2) What is a second processor and what second processors are there?
2.3) Can PC VGA & Multisync Monitors be added to an Acorn machine?
2.4) Are there any cards for IBM PC or compatible machines that Acorn have
produced?
2.5) What is a VIDC enhancer? Will I need one for my new multisync monitor?
2.6) What configuration of serial cable should I use on my machine for modem
work?
2.7) How can I get unfiltered sound from an Acorn machine?
2.8) Can I connect a SCART monitor to my Acorn machine?
2.9) I want to attach an IDE hard drive to my machine, which drives work
with it?
Section 3: Configuration.
-------------------------
3.1) What is ADFSBuffers and what is the best setting for it?
3.2) How do I enable solid drags in RISC OS 3?
Section 4: Hardware problems.
-----------------------------
4.1) My hard drive gives me disc errors when I use, what do the error
numbers mean?
4.2) My disc gives me a 'Broken Directory' or my Free Space Map is corrupt,
what can I do?
4.3) What does the power on self-test check and how does it signal errors
back to you?
4.4) My Real Time Clock has paused, how do I restart it?
4.5) Being of a non-humanoid race I don't have hands, only tentacles. Are
there alternatives to the keyboard for data entry into Acorn machines?
Section 5: Software Issues.
---------------------------
5.1) When using DOS discs I often find the last parts of files haven't been
written correctly, what am I doing wrong?
5.2) 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?
5.3) What is the current File-type allocation ranges and why won't Acorn
provide a full file-type list?
5.4) Is there a Modula 2 compiler for the Arc?
5.5) What version of module X can I assume that all users have?
5.6) What's the minimum version of module X that my program needs? What
features were introduced/what bugs were fixed in which versions?
5.7) What Public Domain Languages are available for Acorn machines?
5.8) Why does the RICS OS 3.5 desktop outline font occasionally revert to a
fixed size system font?
Section 6: Viruses.
-------------------
6.1) How can I protect against viruses?
6.2) Where can I obtain !Killer?
Section 7: Net resources.
-------------------------
7.1) What archives/FTP sites are available?
7.2) What Acorn related companies are available on the net via email?
7.3) Why have there been no postings to comp.{binaries,sources}.acorn
recently?
7.4) How to retreive the FAQ from the source... { Or how to use my email
server. }
7.5) What WWW pages are out there for Acorn topics?
Section 8: Compatibility with other Machines.
---------------------------------------------
8.1) How compatible with other systems is an Acorn machine?
8.2) Is there a BBC BASIC for other machines?
8.3) Can I run the BBC Emulator on the Risc PC?
8.4) Can I read BBC B formated discs on a PC?
----------------------------------------------------------------------------
Section 1: Acorn Hardware and Operating Systems
----------------------------------------------------------------------------
1.1) What is an Acorn machine?
Acorn computers are a British built line of computers that started with
6502 based machines and now are based on ARM processors. Oddly enough Acorn
computers are made by Acorn Computers ( see <http://www.acorn.co.uk/> for
more details.) Section 1.2 details those machines currently in manufacture
and how to fetch a full list of all machines known to have been made by
Acorn. Acorn machines are known for their innovation, flexibility and
reliability of hardware/software.
Reading through section 1 should give newcomers to the Acorn scene a
reasonable appreciation of what the machines can do by default. They are
fairly strong in education and it is Acorn's primary market.
----------------------------------------------------------------------------
1.2) What kind of Acorn machines are there?
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 those currently
manufactured by Acorn. A full list is maintained in my email server under
the filename 'MachineLst'. (section question 7.4 for how to use my email
server.) 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.
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 A30x0
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
Acorn Risc PC series
This is the next generation and architecture of machines -
superceding, 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
management 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. Real-time
video from the IO system becomes a reality with high speed and data
transfers 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.)
----------------------------------------------------------------------------
1.3) What versions of the processor are there and what are their
capabilities?
The details of all current ARM chips and their capabilities are contained
within a file stored in my email server, the filename is 'ARMChips'. See the
instructions near the end of the FAQ for requesting this file.
----------------------------------------------------------------------------
1.4) 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'.
----------------------------------------------------------------------------
1.5) 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 independantly of the application supporting it.)
-Applications can have up to 28Mb of memory apiece, 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
extensions to the OS including the provision of new dynamic areas, extended
podule support, hard drive locking and a wealth of other features.
----------------------------------------------------------------------------
1.6) 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. Resolutions
possible :-
X res. Y res. Colours
640 256 2
320 256 2,4
160 256 4,16
As well a Teletext character graphics mode and two text only modes
were provided by default. The palette range was 16 colours with
modes using less than 16 colours capable choosing any mix of the 16
colours, up to the number displayable of course, for display.
8 MHz ARM based machines. This is the original Archimedes range of
machines and covers the A300 series, A400 series, R140 and A3000
machines. The increased capability of the VIDC1a chip dramatically
enhanced the resolutions and colours depths possible, namely :-
X res. Y res. Colours
160 256 4,16,256
320 256 2,4,16,256
640 250 4,16
640 256 2,4,16,256
640 480 2,4,16,256
640 512 2,4,16,256
1056 250 16
1056 256 16,256
1152 896 2
As can be seen this quite a wide variety of default screen modes.
Most are provided to allow driving the various kinds of monitors out
there easier, since they are suited to that monitor. The palette
range was 4096 colours (12 bit) but the VIDC1a only had 16 hardware
palette registers. This meant that in screen modes with sixteen
colours or less then the colours could be mapped to any of the 4096
available.
However in 256 colour modes 4bits of the colour data are hardware
derived and cannot be adjusted. The net result was in a 256 colour a
block of 16 colours could be assigned as desired with that block of
16 covering a range of the 4096 available colours.
12 MHz ARM based machines. This covers the A3010, A3020, A4000, A4, 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 provided
true PC VGA style compatibility for monitors instead of a 24 MHz
'faked' version which sometimes caused problems with intolerant VGA
monitors.
X res. Y res. Colours
160 256 4,16,256
320 256 2,4,16,256
640 200 2,4,16,256
640 250 16
640 256 2,4,16,256
640 352 2,4,16,256
640 480 2,4,16,256
640 512 2,4,16,256
768 288 2,4,16,256
800 600 2,4,16
896 352 2,4,16,256
1056 250 16
1056 256 16,256
1152 896 2
Because the display hardware was essentially the same as the 8MHz
machines' the palette handling was identical.
Risc PC machines. 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
160 256 4,16,256
320 256 2,4,16,256
640 200 2,4,16,256
640 250 4,16
640 256 2,4,16,256
640 352 2,4,16,256
640 480 2,4,16,256
640 512 2,4,16,256
768 288 2,4,16,256
800 600 2,4,16,256,32k*,16M**
896 352 2,4,16,256
1024 768 16,256*,32k**
1056 250 16
1056 256 16,256
1152 896 2
1280 1024 4,16*,256**
1600 1200 16*,256**
* Requires 1 MB of VRAM
** Requires 2 MB of VRAM
With the addition of Video RAM (VRAM) to the Risc PC the base
capabilities are a touch variable, thus the note next to some of
entries. All other modes are available with standard DRAM.
Furthermore the new VIDC20 has 256 palette registers, compared to
the VIDC1a's 16, and a palette range of 16 million colours. Exactly
how the colour mapping in 32,000 modes is handled is not yet clear.
Again these are just standard screen modes provided, and even
perhaps not all of them - the Risc PC is completely configurable in
display resolutions and capabilities.
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.
----------------------------------------------------------------------------
1.7) 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.
----------------------------------------------------------------------------
1.8) What is the current status of Linux for Acorn machines?
Due to the rapid development of Linux exact details about the latest incarnation of Linux are not kept in this FAQ. However for the latest information you might like to consult these web pages, or email the people involved with the port :-
Native Linux page :-
<http://whirligig.ecs.soton.ac.uk/~rmk92/armlinux.html>
rm...@ecs.soton.ac.uk
PC card Linux :-
<http://www.ph.kcl.ac.uk/~amb/linux.html>
a...@physig1.ph.kcl.ac.uk
----------------------------------------------------------------------------
Section 2: Upgrades and Expansion.
----------------------------------------------------------------------------
2.1) What are the memory limits of the various 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 Mb maximum through third party, 1 Mb official limit.
A4xx - 8 Mb maximum through third party, 4 Mb official limit.
A4xx/I - 8 Mb maximum through third party, 4 Mb official limit.
A3000 - 8 Mb maximum through third party, 2 Mb official limit.
A540 - 16 Mb maximum.
A5000 - 8 Mb maximum through third party, 4 Mb official limit.
A4 - 4 Mb official limit.
A30x0 - 4 Mb official limit.
A4000 - 4 Mb official limit.
A5000 - 8 Mb official limit. (alpha variant of the A5000)
Newer RiscPC machines have an official upper limit of 256 Mb, plus 2
Mb of VRAM, on all models. However this does require you using 128 Mb
SIMMS which are currently not very common...
----------------------------------------------------------------------------
2.2) 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 1 second processor.
4 MHz RAM. (At a 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.
----------------------------------------------------------------------------
2.3) Can PC VGA & Multisync Monitors be added to an Acorn machine?
It depends on what monitor you have, and what Acorn machine 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 separate 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 negligible.
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 incorrect.
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 satisfactorily. The video signal loses the green component
when seperate syncs is selected. It has been reported to me that
400/I series machines may have this fault corrected and not lose
the green component.
As standard, there is no polarity control over the syncs. In
common with the A3000, there is only a 24Mhz crystal. Also it is
links 1 and 2 that need changing.
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 continuously. There is only a 24Mhz
crystal, and only composite sync monitors can be used. Also the A300
suffers the same problem as the A400, it looses green component in
seperate sync mode.
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 series machine to handle the needed
timing and signals.
----------------------------------------------------------------------------
2.4) 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.
----------------------------------------------------------------------------
2.5) 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.
Note a VIDC enhancer is unneccesary and incompatible with the RiscPC
range of machines.
----------------------------------------------------------------------------
2.6) What configuration of serial cable should I use on my machine 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 completely.
With the advent of the Risc PC a standard PC cable is advised.
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2.7) How can I get unfiltered sound from an Acorn machine?
All Acorn machines are equipped with a sound filter designed to remove
high frequency harmonics from the sound output. However this does cause a
muffled feel to the sound as on some machines the filter is a little too
excessive and it filters out valid frequencies. Also the filter is optimised
for 20.833 kHz output and has less desirable results when the output rate is
changed. Accordingly people who do audio work often want to bypass the
filter.
On all machines bar the A3000 there is the Internal Auxiliary Audio
Connector (usually called link LK3), which can be easily plugged into to
provide the unfiltered output. This connector has 10 pins on it and is
usually found near the headphone socket on the motherboard. The pins are :-
1 Unfiltered Left
2 Ground
3 Filtered Left
4 Ground
5 Auxiliary Input
6 Ground
7 Filtered Right
8 Ground
9 Unfiltered Right
10 Ground
Simply hook into the Unfiltered outputs.
On an A3000 you need two 10uF 16V ALEC capacitors. Look for chip LM324
(IC39) and hook the capacitors like this :-
Pin 1 --> --|+ |--- Unfiltered Left
Pin 2 --> --|+ |--- Unfiltered Right
The Risc PC & A400 machines have a connector similar to the A5000.
There are several caveats to this procedure. Opening your machine may
void your warranty and most definitely should not be attempted if you are
unsure of the procedure. Do *not* unplug/plug the unfiltered audio output
while the machine is turned on, by bypassing the filter you also bypass the
normal protective circutry for the audio output.
Finally you will hear higher harmonics present in the audio signal so you
will need to connect the signal to a filter of some kind to reduce this
extra noise.
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2.8) Can I connect a SCART monitor to my Acorn machine?
If you have an older Acorn machine with a nine pin video socket, then
yes and here is the wiring diagram :-
.------------------------. Arc 9-pin plug
\ 1 2 3 4 5 /
\ /
\ 6 7 8 9 / Case
'------------------'
_____________________
|19 1| SCART 21-pin plug
| | | | | | | | | | | |
/ |
/ | | | | | | | | | | |
/___20_________________2_| 21 (metal casing)
A SCART connector is also known as a Euroconnector or a Peri-Television
connector.
Arc SCART
Case | ------------- 21 Case
Red 1 ------------- 15 Red
Green 2 ------------- 11 Green
Blue 3 ------------- 7 Blue
CSYNC 4 ------------- 20 Composite video input
Ground (0V) 6 -+---------+- 13 Red ground
Ground (0V) 7 -+ +- 9 Green ground
Ground (0V) 8 -+ +- 5 Blue ground
Ground (0V) 9 -+ +- 13 CVBS video ground
Ideally each ground wire should be linked to a separate Arc pin. Also,
depending on your SCART monitor, pin 16 may need a +5V input to it.
Unfortunately the Arc 9 pin socket does not provide a +5V output so this
will have to be sourced from somewhere else.
If you have a newer Acorn machine, with the 15 pin high density video
socket then you need this kind of wiring :-
.--------------------. 15-pin VGA style plug
\ 1 2 3 4 5 /
\ 6 7 8 9 10 /
\ 11 12 13 14 15 /
'--------------'
Connections:
Arc SCART
1 red ---------------------------- 15
2 green--------------------------- 11
3 blue---------------------------- 7
4 ID[2] nc
5 0V (test)
6 red rtn------------------------- 13
7 green rtn----------------------- 9
8 blue rtn------------------------ 5
75 ohms
9 +5V-------------/\/\/\/--------- 16
10 0V----------------------------- 17,18
12 ID[1]-------------------------- 8
11 ID[0] <--13 |
13 HSync -->11 |
120 ohms
14 CSync------------/\/\/\/------- 20
15 ID[3] nc
Notice the two resistors. Also notice that the HSync output (pin 13) of the
15-way plug has to be connected to the ID[0] input (pin 11) of the same
plug. (Be aware I have no direct confirmation that this wiring *works*.)
As is usual care must be taken when doing this procedure. Older Acorn
machine did not have their VIDC chips fully buffered and unplugging/plugging
cables from the video socket while the machine is turned on can cause
damage to the video circutry.
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Q2.9) I want to attach an IDE hard drive to my machine, which drives work
with it?
Here is a list of IDE drives known to either work or not work with Acorn
hardware. If the drive appears with no notes then it will work fine with the
machine specified. This list is maintained by Toby Smith
<t...@cs.bham.ac.uk> and all corrections, additions and updates should be
emailed to him.
The IDE Drives & Interfaces "What Works With What" list
+++++++++++++++++++++++++++++++++++++++++++++++++++++++
Manufacturer Part Number Size Interface Notes
Conner CFS540A 540 Std/RiscPC
Conner CFA540A 540 ICS Doesn't work on std Acorn i/f
WstrnDigtl Caviar 2540 540 Std/RiscPC <DOESN'T WORK> E-IDE
Quantum 540 DT Soft Format to 512M
WstrnDigtl Maverick (?) 540 Std/RiscPC E-IDE
Conner CFA540A 540 Std/RiscPC WILL NOT WORK
Conner CFS540A 540 Std/A5000 S-CP3044
Fujitsu M2684TAM 528 ICS Real 504Mb S-H3171-A2 [3]
Seagate ST5660A 528 Std/RiscPC Format to 512M (1039 Cyls)
IBM 528 Std/RiscPC Odd Noises! [3]
Conner CFS420A 420 Std/A5000 M-CP3044
Conner CFS420A 420 Watford
Seagate 420 ICS
Seagate 420 ICS
Cooner CFS420A 420 Std/A5000
Conner CP30424 (?) 420 ICS Internal PSU
Conner CFS420A 420 Std/RiscPC #
Seagate ST3491A 408 [2]
Fujitsu M286T 340 Watford M-S-NEC D3756
Fujitsu M2682T 340
Maxtor 7345S 340 Std/RiscPC <DOESN'T WORK> [1]
Conner CP30254 250 ICS M-CP3044 S-CFS420A
Conner CFS210A 210 Std/RiscPC #
WstrnDigtl Caviar 200 Std/AnyAcorn WILL NOT WORK
IBM H3171-A2 171 ICS M-M2684TAM. Real 163Mb
Conner CP30174E 170 Std/A5000
Maxtor 7120 130 ICS Disable on-disc cache. (ICS util)
SyQuest SQ3105 AT 105 Std/A5000 M-CP3044 S-CFS420A
NEC D3756 100 Watford M-S-M286T
Rodime RO3139AP 100 Watford Works alone, wont co-exist.
Maxtor 7080 85 ICS Disable on-disc cache. (ICS util)
Conner CP3085 (?) 85 ICS Running of computer's PSU too!
Maxtor 80 ICS (FS 2.03)
Conner CF3008E 80 Std/A5000,A4000 # Wont S/M CFS420A, without link.
Seagate ST51A/X 40 Std/RiscPC S-CFS420A
Conner CP3044 40 Std/A5000 # S-SQ3105 AT
Seagate ST351A/X 40 Watford IDE
Conner CP3044 40 ICS (FS 2.03)
PrairieTek 20 ICS (FS 2.01)
Enlargements to notes:
[1] Aparently works with the contributors home made IDE interface!
However, someone else said that the 'S' meant it was a SCSI device????
[2] Seagate ST3491A Wont S/M to CFS240A (High end A5000). Will slave to
CFS420A (Risc PC)
[3] This drive recalibrates for thermal adjustments every 10mins, making a
click.
Understanding the list:
1. Interface = 'Std/****' indicates the IDE interface provided with the
specified machine as part of the standard purchase package.
2. M-XXXXXX -Master to drive (part number given)
S-XXXXXX -Slave to drive (part number given)
3. A '#' in the notes section indicates a drive provided packaged with the
specified machine.
4. Sizes quoted are the 'manufacturer' sizes (for purchasing reference)
remember that manufacturer Megabytes are 1000K, whereas formatted
megabytes are 1024K... to get the 'real' size, multiply the number given
by 1000, then divide by 1024.
5. Master / Slave information usually refers to other drives in the list!
Disclaimer:
This list reports the reported experiences of others. Neither
the maintainers, nor the contributors are definately saying that these
combinations will work - just that they have for them. So don't sue us!
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Section 3: Configuration.
----------------------------------------------------------------------------
3.1) 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 improvement 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 reformatting 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 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.
RISC OS 3.5 seems to have all of these problems cured and no new bugs
introduced. Under 3.5 the number of ADFSBuffers can be left at the OS's
discretion and generally the OS chooses a number based on the amount of
memory present in your RiscPC.
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....
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