ARM Club 3/TheARMClub_PDCD3.iso/hensa/documentation/documents/a252mon

Internet Message Format | 1999-04-27 | 19KB

From: [e-mail] (Ian Palmer)
Subject: Re: Monitor Recomendations
Date: 24 Nov 1993 13:25:04 GMT

Ewen ([e-mail]) wrote:
> Hello folks,
> My trusty old Acorn colour monitor has just gone kaput and I'd like to
> replace it with a reasonably priced Multisync job. I'm going to the
> computer shopper show, and I'd like to buy it then, anybody got any
> recomendations, hints, or warnings?

> My computer is an Archimedes 310 with ARM3 RO3.1, 4Mb and SCSI HD
> is there anything else I'll need to do to it?

The word minefield comes to mind here. First of all you would really
need a VIDC enhancer in your 310, then there is the problem that (I
would imagine) your 310 can't produce seperate syncs without an
alteration - and there are quite a few multisync monitors around that
require this. Next there is the connector, most monitors today come
with a 15 pin connector, where as the 310 probably only has a 9 pin
connector (you can get a converter for this though).

Now the fun really starts, locating a monitor. Now you really need to
consider your needs here. Ie. do you play games. The problem is that
most games for Arc use low res modes with a vertial scan rate of
15.whatever kHz (TV scan rate if memory serves). Now you can activate
the VIDC enhaner to increase this, but some games will fail to work
(Zool goes too fast, Turbo challenge fails to read the keyboard for
some reason, are just two examples - but many will work o.k.).

So if games are very important to you, you really need a monitor which
has a scan rate that goes down to 15.whatever-it-is kHz, but for the
multisync modes you really need to also have one that goes upto the
30-odd kHz range (can't remember the exact value off hand, probably 36
- what ever the VIDC enhancer rate is, monitors in this range tend to
go upto 38 kHz or there abouts (to get one which goes much higher than
this is pointless unless you get a graphics card).

Now the problem is that not many monitors go from 15.whatever to
38-ish, I can think of 4 off hand (well 5 actually). These are the
Eizo 6080 (or something like that, expensive in any case), the
MicroVitec 1440, the Acorn AKF18 (crap, and expensive with it (well
for what you get it is expensive)), and the new Acorn AKF50 (rebadged,
reworked MicroVitec 1440 without the programmability, but with
standard Acorn modes pre-programmed, and cheaper)).


Ian
---
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                  (The Book of Stupid Lists)
    ___           _                         Ian Palmer, Department of Computing,
     /  _   _    /_) _   / _ _   _  _       Imperial College, 180 Queen's Gate,
____/__(_|_| )__/ __(_|_(_| ) )_|/_) _______London SW7 2BZ. England.____________




From: [e-mail] (Tom Crossland)
Subject: Multi[Sync/Scan] Monitors (Summary of Responses)
Date: 5 Oct 92 18:23:16 GMT

Thanks to all who replied to my original posting. Here is a summary of
responses...

>Can anyone recommend some good multisync (multiscan, etc) monitor to use
>on an Archimedes? I don't want to spend TOO much on it, just something
>that looks good in hi-res modes.

----- From: [e-mail] -----------------------------------

the Panasonic multi-sync I bought from Watford a year and a bit back
was inexpensive and just about perfectly matched to the Arc.  It is
still working flawlessly too... (albeit attached to a 486 PC these days).

The Panasonic was 240 or 260 pounds + VAT around 18 months ago.

----- From: [e-mail] (Graham Allan) -----------------------------------

I have an AOC multiscan monitor - I forget the model number - which I
have recommended in the past (and still would). It's not as solidly
built as Taxans etc, but at about UK#235 its about half the price. It
will display the standard 50Hz screen modes as well as those extra
high-resolution ones produced by a VIDC enhancer. Picture quality is fine.

I got my monitor from College Computers. The first one died after 4
days but the replacement is fine. I can't say much
about the failure of the first one, these things happen...
(their quality control may be not as good as more
expensive makes, but any fault due to that would
occur during the first 2-3 weeks anyway).

----- From: [e-mail] ----------------------------------------------

I'm waiting for the arrival of an Eizo 9060s I ordered a week ago
from Watford, having used a Philips CM8833 (same as Acorn's standard
medium res Arc monitor) for the past five years; they charge #389+VAT
& carriage (carriage to Ireland is #12, so not a big cost) for it;
if that's within your price bracket I'll let you know what I think
when it arrives..

>From what I hear, the Taxan (795?) has good colour reproduction, but
the Eizo has a sharper picture and so is better if you're more into
text than art..

----- From: Jon Thackray <[e-mail]> ------------------------------------

I've just bought an Eizo 9060S, which *wasn't cheap*, but before doing so,
I was looking at cheap multisyncs. The short answer is, there aren't any.
(good ones, that is...)

The cheapest I found was an AOC CM326, at #249+VAT from most PC dealers, but
when I came to buy it, found it was discontinued. Besides, that couldn't even
do 1024 x 768 non-interlaced (a common test for PC SVGA monitors), so in the
end, I decided to lash out for this one - and worth it - I would say. If it
saves me eye-strain in the long run, it's worth it - mine goes up to 90Hz,
although most of my Arc modes aren't defined past 70Hz.

I haven't had any trouble switching modes, all the knobs are on the front
underside, as rotary switches, the manual leaves a bit to be desired, and
the model has been around for a couple of years at least, but quite a
few people have them.

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



From: [e-mail] (Brian Brunswick)
Subject: Re: multi-sync monitors
Date: 1 Mar 91 10:40:26 GMT

>I am about to buy an A540 + multisync monitor ...
>The monitor I am specifically interested in is the Taxan 795, ...

Ok, I'll jump to this one, since I posted about the Taxan a while back.

There are basically two parameters to a mode that affect whether it
can be displayed by a given monitor - the horizontal sync rate and the
frame rate. For a normal TV, the hrate is 15KHz, and the frame rate
50Hz - so thats 300 lines (These figures are approximate) The standard
multisync modes like 20 double the hrate to 30KHz, and get 600 lines.

The trouble with the 795 (which is otherwise very nice) is that it can
only handle horiz rates of 30-57KHz, so any standard mode won't work,
though the multisync ones will.  However, it is possible to modify the
format of existing modes to bring them into this range. This is done
by loading a patch module - So if its a game that runs by some boot
sequence that you can't get at, you're well Zogged, as certain people
in Cambridge might say.

There are two other issues here as well. Firstly, a standard Archi can
only chuck pixels out at 24MHz, and with 8MhZ memory has a total
memory bandwidth of about 25Meg/s. So not all existing modes can have
their line rates increased sufficiently. There are hardware add ons
which increase the max pixel rate to 36MHz, but you are still stuck.
With a 540, I understand (check me on this) that it has such a mod
built in, and also has 12MHz memory. So these figures go up, and its
easier to fix things.

Secondly, a lot of games take their timing from the fram rate.  If
your replacement mode uses a different frame rate, games will
(attempt, and with an 540/ARM3 do quite well usually) to run fast.
However, the frame rate can easily be reduced by leaving large gaps
above and below the data, and adjusting the monitor to expand it
vertically - make sure you get a version of the patch module with this
ability.

Basically, for the Taxan795, make sure you see it running before you
buy, switch modes around, find out how to adjust it, and work out
whether you personally can stand the irritation.

But its a lovely picture - I recommend it.
[e-mail]  Disclaimer.  Short sig rules!



From: [e-mail] (Owen Smith)
Subject: Re: Monitor for both Arc and VGA PC
Date: 22 Nov 91 13:21:37 GMT

>Which of the various multisync types would be the best bet, based on
>people's experience? I want one which gives minimal hassle - ie : there
>shouldn't be problems with screen centring etc....

I would strongly recommend the Eizo 9060S, which I have been using for
a year now. Screen centering is fine on all standard modes, and most
of the AtomWide and CC extra modes. Some of the extra modes need moving
a bit, but the controls on the Eizo 9060S are flexible and more to the
point the monitor does what you tell it rather than trying to get clever
and failing (many Taxan and NEC monitors suffer from this).

The important thing is to match the monitor to the Archimedes. All the
monitors are designed to work with PCs, so that PC should not be a
problem. The other thing to watch for is monitors which are not truly
multisync. The cheaper monitors have simple circuitry which says "is
this signal CGA, EGA or VGA?" and set themselves up appropriately. These
monitors have problems on the Archimedes, because some of the modes do not
fit any of the PC standards. You want a truly flexible monitor which just
displays whatever is sent to it. (The Eizo 9060S is of this type.)

I would recommend against the Taxan 795 - it won't run slow enough for the
standard Archimedes modes so you have to use fiddled versions of the modes
with lettering boxing and stuff, and also games which time on the VSYNC
tend to run fast due to refreshing the screen faster to get the pixel
rate up high enough for the 795 to work.

Owen.

The views expressed are my own and are not necessarily those of Acorn.



From: [e-mail] (Graham Allan)
Subject: Re: Multisync monitors
Date: 9 May 92 14:13:32 GMT

I eventually managed to find a *cheap* multisync which works in all the
Archimedes screen modes. This is made by AOC, model number CM-326. I'd never
heard of the name, but looking round the physics department here noticed a
few assorted AOC monitors which looked okay, and as if they'd lasted 3 or 4
years. The CM-326 costs around #240; I got mine from College Computers but
lots of PC dealers probably have them.

The AOC will scan the 'standard' modes 0-16 & 24, and the multiscan and VGA
modes, plus any custom modes defined with a VIDC enhancer. I would imagine
it's designed to go up to the SVGA spec. Resolution is up to 1024x768 with
0.28" dot pitch (standard Acorn is 0.42", to compare). The picture is
reasonably sharp and clear; not quite up to a Taxan 795 - but it is about
half the price. The tube itself is made by Panasonic, so is probably not
bad. Only disadvantage is having to recentre the display when changing
between multiscan / custom / standard modes - but that's a common problem.
Only the horizontal centering needs tweaking so its not a big deal. The only
other operational difference from a Taxan or Eizo is the amount of shielding
(there isn't any) - the microwave in the kitchen is the other side of the
wall from the monitor, and when it's running, the picture goes all wavy (as
if introducing a 'dream' sequence in a bad 60's movie)!

There is a word of warning, though - I suspect a lot of the difference in
cost between cheap and expensive monitors is due to the amount of quality
control at the factory. The first sample I got died after 3 days. The
replacement one I have now has lasted a month so will probably be okay - if
a piece of equipment like this can last for 10 days continuous running, then
its likely to last for a few years; any badly out of spec component will
generally fail in the first few days.

Graham Allan
Physics Dept., University of St. Andrews



From: [e-mail] (Andy Mell)
Date: 10 May 92 01:47:14 GMT

>Is there a multisync monitor that works well with the Archimedes
>in all modes?  What is it?

*THE* monitor for the archimedes has to be the Eizo 9060S, it displays all
modes fine, it can scan analog between 15.5kHz and 38.5kHz, you do have to
adjust it for SVGA modes (per 540,260,5000) but all normal and msync modes
work fine. The picture is bright and clear. Easy access to the controls.

BTW: If you are thinking of buying an Eizo from a PC dealer, dont, get it
from a reputable archimedes dealer as Eizo set up the monitors internals
specifically for the archimedes, they are a different model to the normal
PC Eizos.

Andy
(Yes you guessed - I have an Eizo, and its a hell of a lot better than
any other monitor that I have seen on the Arc)



From: [e-mail] (J M Fielder)
Subject: Re: VGA monitors for the Arc
Date: 28 Apr 92 10:04:03 GMT

>Since you can buy PC VGA monitors which now seem to scan frequencies upto
>SVGA fairly cheaply, is it possible to connect one of these monitors to an Arc?
>If anyone has got a PC VGA monitor on their Arc, what model is it, how good is
>it, and what pin connections do you have to make to the connector on it.

Seeing as this is coming up more and more, how about adding the below to the
FAQ?

Question: Can PC VGA Monitors be added to an Archimedes?

Answer:   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 determin 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.

      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 upto 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.i

         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
         determin 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 Watford Electronics VGA VIDC
         Enhancer for the A3000 (See below)

         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.

     Concusion:
     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 satisfactorly (how do you spell that?)

[Note, the below is probably an advert, and I make no mention of any other
VIDC enhancer, as there is no other that can generate composite syncs, and
has the 25.175Mhz crystal needed for correct video timings]

The Watford Electronics VGA VIDC Enhancer
    Available in two versions.

    A300 / A400 series
       If you have an A300 series computer, then your motherboard needs some
       surgury (?) on it to create a header for the expansion. Any 'competent'
       person can do this, or any local dealer will probably do it for #10
       or so......

       The VIDC Enhancer provides three functions.

       a) To split up the composite sync generated by the archimedes (so the
       video isn't disturbed) into horizontal and vertical seperate syncs.

       b) To provide software control over the sync polarity

       c) To provided software control over VIDC's clock rate. There is a
      25.175Mhz and 36Mhz crystal on the VIDC enhancer.

       Supplied with the VIDC enhancer is some new modules that re-map ALL
       pratical modes (modes 0-15, 7 included) to the new higher line rate.
       These modes have been 'pre-optimised' for various VGA monitors
       already.

       Also supplied is a mode defining utility with alows software control
       over the clock rates, sync polarities, and will make a mode that
       matches defined line and frame rate for fixed frequency monitors.

       Supplied also is a 'tweaking' utility. Some monitors will display some
       modes 'off centre', with the result that you have to fiddle with the
       controls. With the WE software, leave the controls in a centeral
       position, and the screen can be 'moved around' the monitor until
       it is centeral.


    A3000 version
       Exactly the same as above, except the seperate syncs are generated
       by the Archimedes rather than the VIDC enhancer.


There is no WE software only for the A540 computer to re-map all of the modes.


Hope that helps..........

Joust