Best LCD for IIGS
Drew
Been doing some research and testing of Apple IIGS connected to
various TVs with RGB scart and have had very varied results and still
haven't really found a currently available LCD monitor that seems to
sync fully (used standard VintageWare RGB Scart cable and also one
that i modifed to sync on composite) or look very good. I am not sure
that LCD will look very good anyway even if i was able to get one that
did sync properly due to the way LCDs display low res content.In my
process of testing lots of TVs I did find try a friends 14inch Sony
CRT Trinitron (KV-14LT1U) which was really good quality very close to
RGB monitor (though was better in other aspects due to newer tube i.e
brighter etc), and have infact picked one up off ebay for £10 :-) as
it was so good. Though this isn't very practical for me at the moment
due to space on my computer desk. Though the monitor is quite a newish
monitor, think in the last 5 years.
I am trying to find a 20/22inch LCD that will work with a GS and allow
me to use my PC happily and is currently a model that is still for
sale. Ideally the LCD should support PIP etc as find it quite handy to
have GS on small screen at points (current monitor has composite input
and PIP). Don't want much do i ;-)
I was wondering what people had tried? I know a Samsung 910mp (though
not forsale anymore as far as i can tell) should work and I myself
have tried a Samsung 220HD monitor which wasn't too bad (but it costs
£300), but didnt support PIP and the picture quality wasn't as good as
the 14inch CRT, but this might be the fact it was an LCD and was
22inch screen.The main thing was the black text seemed to have a bit
of shadow. I did also try an LG 19inch in PCworld and that was awful
output, looked like a composite output.
I will post some links to pictures from the 220HD for comments if this
is what i can expect from an LCD.I have been thinking i might go for
the 20inch version which won't be trying to stretch the low res so
much and is about £230.
Cheers
Drew
Drew
Have put some photos here:-
Several pictures listed as T220...etc. Looking at the photos doesnt
look too bad actually lol.
Drew
schmidtd
> I am trying to find a 20/22inch LCD that will work with a GS and allow
> me to use my PC happily and is currently a model that is still for
> sale. Ideally the LCD should support PIP etc as find it quite handy to
> have GS on small screen at points (current monitor has composite input
> and PIP). Don't want much do i ;-)
half ago. I don't know if they're still for sale, but the reason I
bought it was because it has every connector known to man+dog on it.
SCART, composite, SVideo, component, and VGA. It's widescreen, and so
does the PC at 1440x900 or so. It might be just 20" diagonally. My 8-
bits (and the Mac IIci) put out a less wide picture, so that's
centered. I am typing from my PC now with the IIgs running in the PIP
window.
It looks great in all modes. Except maybe when hooked to older II+
computers that took such liberties with the NTSC signal... they look
pretty crufty.
Conrad
Has anyone tried using this to connect the GS to a VGA Monitor.
http://www.ambery.com/rgbcgatovgac.html
It seems to be like the XRGB, just a hell of a lot cheaper. I'm
thinking about getting it and trying it out, but I dunno if it's
compatible. Any thoughts?
Drew
Hi,
Interesting there seems to be some models of the 940MW that don't have
the other connectors just DVI and VGA. Do you run a GS of it? Shame
resolution isn't a bit higher, I have got used to 1680 by 1050 :-).
Drew
Drew
>
> - Show quoted text -
Couple of Samsungs I like the look of are the Samsung SM-2032MW and
the Samsung SM-225MD 22" HD Ready Widescreen, but can't find anywhere
local that sells them in an actual shop so I can try, so would be
interested if anyone has one of these and uses it on a GS.
Drew
Bill Garber
"Conrad" <conrad...@gmail.com> wrote in message news:774afac8-c8af-48cb...@s20g2000prd.googlegroups.com...
Look for thread "Video Converters" There is one I had asked
about that is 'way' cheaper yet. Oh, heck, I'll just repost
the link. This one is actually mentioned in the FAQs.
http://baysoftgames.stores.yahoo.net/vgabox1.html
I'm going to try this one, if money warrants it.
Bill Garber from GS-Electronics
http://www.garberstreet.com
Michael J. Mahon
I've always suspected that having a KVM switch between a modern hi-res
computer and a IIgs converted to VGA would be a real let-down. Doing
the "A-B" comparison quickly on the same screen really highlights the
difference in resolution!
My Apples are in the room next door, so when I get up, walk a bit, and
sit down at the Apple II, I've transitioned to another world--one in
which 280x192 is "hi-res". ;-)
-michael
AppleCrate II: An Apple II "blade server"!
Home page: http://members.aol.com/MJMahon/
"The wastebasket is our most important design
tool--and it's seriously underused."
Michael J. Mahon
That would be *all* Apple II's except the IIgs... ;-)
It appears that modern digital TVs don't do a very faithful job of
emulating older analog TVs--as you might expect.
Drew
>
> - Show quoted text -
Tried a SM-2032MW today, picture quality looked liked the Samsung
T220HD but had serious motion blur and refocus when moving the mouse
around, so avoid that model for use with a IIGS with RGB Scart. Also
tried a couple of small 15 inch LCDs by Philips and Polariod all
looked about as good as composite..search continues...
Drew
Jeff Blakeney
On Sat, 13 Sep 2008 17:41:28 -0400, Bill Garber wrote:
> "Conrad" <conrad...@gmail.com> wrote in message news:774afac8-c8af-48cb...@s20g2000prd.googlegroups.com...
>>
>> Has anyone tried using this to connect the GS to a VGA Monitor.
>>
>> http://www.ambery.com/rgbcgatovgac.html
>>
>> It seems to be like the XRGB, just a hell of a lot cheaper. I'm
>> thinking about getting it and trying it out, but I dunno if it's
>> compatible. Any thoughts?
>
> Look for thread "Video Converters" There is one I had asked
> about that is 'way' cheaper yet. Oh, heck, I'll just repost
> the link. This one is actually mentioned in the FAQs.
>
> http://baysoftgames.stores.yahoo.net/vgabox1.html
>
> I'm going to try this one, if money warrants it.
That one doesn't seem to take a 15 kHz RGB signal as an input, only
composite, S-Video and component.
The one Conrad mentioned looks quite nice as it converts 15 kHz RGB into
VGA and will also convert interlaced video to non-interlaced
(progressive scan). It would be nice to see the 640x400 interlaced
output of the Video Overlay Card using that device. The extra
functionality I think makes up for the difference in cost. The only
problem is that Apple is not listed as one of the supported legacy
devices. However, the Amiga and Atari computers are listed there and as
they had similar outputs to the IIgs, it is an encouraging sign. If I
had the extra money right now I'd probably pick one up and try it.
Bill Garber
"Jeff Blakeney" <jeff.b...@a2central.com.remove-3ym-this> wrote in message news:nu20u3u78306$.1pn72mrif0wqr.dlg@40tude.net...
> To: Bill Garber
> On Sat, 13 Sep 2008 17:41:28 -0400, Bill Garber wrote:
>
>> "Conrad" <conrad...@gmail.com> wrote in message news:774afac8-c8af-48cb...@s20g2000prd.googlegroups.com...
>>>
>>> Has anyone tried using this to connect the GS to a VGA Monitor.
>>>
>>> http://www.ambery.com/rgbcgatovgac.html
>>>
>>> It seems to be like the XRGB, just a hell of a lot cheaper. I'm
>>> thinking about getting it and trying it out, but I dunno if it's
>>> compatible. Any thoughts?
>>
>> Look for thread "Video Converters" There is one I had asked
>> about that is 'way' cheaper yet. Oh, heck, I'll just repost
>> the link. This one is actually mentioned in the FAQs.
>>
>> http://baysoftgames.stores.yahoo.net/vgabox1.html
>>
>> I'm going to try this one, if money warrants it.
>
> That one doesn't seem to take a 15 kHz RGB signal as an input, only
> composite, S-Video and component.
Sorry, I neglected to mention that I have an RGB to Component
solution. This was mainly mentioned for those looking for a
composite to VGA solution.
There already is an RGB to VGA solution that works quite well,
albeit rather expensive, how many do you need to buy? One should
suffice, I should think, shouldn't you?
Bill Garber from GS-Electronics
http://www.garberstreet.com
"If you wish to forget anything on the spot,
make a note that this thing is to be remembered."
(Edgar Allen Poe)
Drew
Still on the hunt for an LCD that will work with the GS, so decided to
buy a Samsung 940MW which i thought would work ok (from posts on forum
etc), though on plugging a RGB Scart cable into it i get the same
focus/motion blur when parts of the screen change exactly the same as
the SM-2032MW I tried. Picture is stable and colours look ok, just
doesn't seem to cope very well when things change i.e opening menu
etc... any idea why this would be and is it something i can fix via
the RGB cable?
Thanks in advance...
Drew
Charlie
"Drew" <Goggl...@gmail.com> wrote in message
news:49ac0b0c-41d8-4cc5...@l76g2000hse.googlegroups.com...
Drew,
I use a Samsung 940MW with Roger Johnstone's (Vintageware) RGB-SCART cable.
There is a slight banding (vertical lines) where two differ colors meet. I
have always believed that the motion blur you are seeing was the effect of
this banding when you move something on the screen. Looking at it again
after reading your post, I'm not so sure. The trail following the mouse is
longer than one line (considerably). You can see it best on my machine when
you open a window in the finder and run the mouse back and forth over the
striped area of the title bar. I did notice that you can actually see the
mouse arrow change from fuzzy to sharp when you stop. This indicates to me
that there is some kind of delay in synchronizing that is way too long.
Still for me this is the best option, I know of, since I keep both my PC and
my IIgs connected to Samsung 940MW all the time and can even view both on a
split screen.
Charlie
Drew
> "Drew" <GoggleD...@gmail.com> wrote in message
Thanks Charlie, at least I know its not just the one i got. I also
tried a Scart>Component converter box (CSY-2100) and though i got a
picture and and no blur; colours and picture were rubbish.
I think i will end up waiting and getting a Samsung T200HD (which
works fine apart from a bit of ghosting (as all all LCDS that i have
seen) and no PIP) when it comes down in price. Still want to try a
Samsung SM-225MW/MD though as that supports PIP which I would find
very handy....though so far it would seem that the majority of LCDs
don't work correctly with the RGB being outputed from the IIGS....
Thanks
Andrew
Michael J. Mahon
Maybe you are seeing artifacts of digital processing in the monitor.
Since NTSC-rate video must be significantly upsampled to fill a modern
LCD monitor, it's likely that some filtering and edge enhancement is
done, at least for slowly moving or static images.
Sophisticated monitors (more all the time) even do frame-to-frame
interpolations, deinterlacing, and 3:2 pulldown processing (when
it thinks it applies--like when two successive fields are identical).
Sometimes you can use menus to turn these off, and sometimes not...
-michael
******** Note new website URL ********
NadaNet and AppleCrate II for Apple II parallel computing!
Home page: http://home.comcast.net/~mjmahon/
Drew
> Charlie wrote:
> > "Drew" <GoggleD...@gmail.com> wrote in message
Thanks for that. The Samsungs don't have much options in the default
menu. Possibly able to do something via a service/debug menu, will
have a look.
Drew
Charlie
"Michael J. Mahon" <mjm...@aol.com> wrote in message
news:6M-dnQSnaf_862LV...@comcast.com...
Well "sometimes not..." seems to apply here. I've tried the meager amount
of video settings with no real difference.
Charlie
Christopher G. Mason
> Thanks Charlie, at least I know its not just the one i got. I also
> tried a Scart>Component converter box (CSY-2100) and though i got a
> picture and and no blur; colours and picture were rubbish.
> I think i will end up waiting and getting a Samsung T200HD (which
> works fine apart from a bit of ghosting (as all all LCDS that i have
> seen) and no PIP) when it comes down in price. Still want to try a
> Samsung SM-225MW/MD though as that supports PIP which I would find
> very handy....though so far it would seem that the majority of LCDs
> don't work correctly with the RGB being outputed from the IIGS....
>
> Thanks
> Andrew
Andrew,
Are you in the US? I see the international Samsung T200HD model has a
SCART RGB input, but sadly the US model seems to delete that particular
port (doh!). Are you using the VGA in port for the IIgs video on the
T200HD? I know my Samsung 930MP won't take the IIgs' 15.75khz RGB video
from its VGA-in, only the SCART input. Its a silly limitation that I
wish LCD and Plasma displays didn't have as their internal video
processors can easily handle it.
As for the artifacts, its likely from the upscaling of the video to fit
the LCD panel. The IIgs technically outputs 240p (progressive) video,
although the internal processor may handle it as standard 480i
(interlaced) video and add in scanline artifacts as well (the first
field is the IIgs video, the second field is blank). At a minimum you
can turn off the stretching of 4:3 video to 16:9 (if its a widescreen
display). Otherwise you could try using a VERY expensive external video
processor like the DVDO series from Anchor Bay for better results and
tweakability. They will allow you to use any DVI/HDMI equipped monitor
with your IIgs as well.
Drew
Hi,
I am in the UK. I had turned the Scart input to be 4:3, and did look
better. I had also tried the T220HD and the picture was stable and
didnt suffer from bluring, but the monitor didnt support PIP and was
also about £330 pounds (at the time) which i thought was a tad
expensive considering i am really only looking at it so i can use the
IIGS and my PC at the same time. The DVDO looks a bit much lol. The
T200HD goes for about £200, so will probably go with that and not have
PIP. I suppose ideally a device that worked with GS to VGA would be
good but don't believe there is anything that really works and scart
seems the best and cheapest option....though i am building quite nice
collection of CRTs lol
Cheers
Andrew
Steven Hirsch
> As for the artifacts, its likely from the upscaling of the video to fit
> the LCD panel. The IIgs technically outputs 240p (progressive) video,
> although the internal processor may handle it as standard 480i
> (interlaced) video and add in scanline artifacts as well (the first
> field is the IIgs video, the second field is blank). At a minimum you
> can turn off the stretching of 4:3 video to 16:9 (if its a widescreen
> display). Otherwise you could try using a VERY expensive external video
> processor like the DVDO series from Anchor Bay for better results and
> tweakability. They will allow you to use any DVI/HDMI equipped monitor
> with your IIgs as well.
I have no experience with the Anchor Bay unit, but I am very happy with the
results from a Highway Model 100 RGB (Scart) --> XGA converter. Using Roger
Johnstone's cable (I did have to switch the signal used for sync from the
default) it presents a quite reasonable picture with no motion artifacts.
Better still, it's fantastic as a scan doubler for my Amiga 2000! The 640x480
interlaced NTSC mode, unusable on a CRT monitor due to major flickering, just
looks beautiful. Stable as a rock.
The unit was about $220 US when I purchased it, but is well worth it in my
opinion.
Steve
Bill Garber
"Steven Hirsch" <snhi...@gmail.com> wrote in message news:RaOdnUfkUpxGUGLV...@giganews.com...
Did you mean this?
http://www.converters.tv/products/rgb_to_vga/100.html
Bill Garber from GS-Electronics
http://www.garberstreet.com
"If you wish to forget anything on the
Drew
Hi Steve,
Do you have any screenshots of what GS/OS and some GS games (Sierra
ones would be good :-)) look like with the unit?
Cheers
Drew
Steven Hirsch
>> with the results from a Highway Model 100 RGB (Scart) --> XGA
>> converter. Using Roger Johnstone's cable (I did have to switch the
>> signal used for sync from the default) it presents a quite reasonable
>> picture with no motion artifacts.
>>
>> Better still, it's fantastic as a scan doubler for my Amiga 2000! The
>> 640x480 interlaced NTSC mode, unusable on a CRT monitor due to major
>> flickering, just looks beautiful. Stable as a rock.
>>
>> The unit was about $220 US when I purchased it, but is well worth it
>> in my opinion.
> Did you mean this?
> http://www.converters.tv/products/rgb_to_vga/100.html
Yes, that's the unit I have.
Steven Hirsch
> Do you have any screenshots of what GS/OS and some GS games (Sierra
> ones would be good :-)) look like with the unit?
I actually do not own any GS games, sorry. My interests and reaction times do
not run in that direction. I will try to get some general shots of
applications, but I'm not sure how I'll get them to you (no webpage).
Steve
Drew
> "Steven Hirsch" <snhir...@gmail.com> wrote in messagenews:RaOdnUfkUpxGUGLV...@giganews.com...
> > Christopher G. Mason wrote:
>
> >> As for the artifacts, its likely from the upscaling of the video to fit
> >> although the internal processor may handle it as standard 480i
> >> (interlaced) video and add in scanline artifacts as well (the first
> >> field is the IIgs video, the second field is blank). At a minimum you
> >> can turn off the stretching of 4:3 video to 16:9 (if its a widescreen
> >> display). Otherwise you could try using a VERY expensive external video
> >> processor like the DVDO series from Anchor Bay for better results and
> >> tweakability. They will allow you to use any DVI/HDMI equipped monitor
> >> with your IIgs as well.
>
> > I have no experience with the Anchor Bay unit, but I am very happy with the
> > results from a Highway Model 100 RGB (Scart) --> XGA converter. Using Roger
> > Johnstone's cable (I did have to switch the signal used for sync from the
> > default) it presents a quite reasonable picture with no motion artifacts.
>
> > Better still, it's fantastic as a scan doubler for my Amiga 2000! The 640x480
> > interlaced NTSC mode, unusable on a CRT monitor due to major flickering, just
> > looks beautiful. Stable as a rock.
>
> > The unit was about $220 US when I purchased it, but is well worth it in my
> > opinion.
>
> > Steve
>
> Did you mean this?
>
> http://www.converters.tv/products/rgb_to_vga/100.html
>
>
> "If you wish to forget anything on the
> spot, make a note that this thing is to
> be remembered." (Edgar Allen Poe)
This looks the same product just repackaged...but this is available to
me in the UK :-).
http://www.cypuk.com/cyp_techpage.php?product=26&&parent=
Drew
Bill Garber
"Drew" <Goggl...@gmail.com> wrote in message news:503bb19c-5b43-4fd1...@d1g2000hsg.googlegroups.com...
On 23 Oct, 02:55, "Bill Garber" <willy4...@comcast.net> wrote:
>>
>> Did you mean this?
>>
>> http://www.converters.tv/products/rgb_to_vga/100.html
>
>me in the UK :-).
>
>http://www.cypuk.com/cyp_techpage.php?product=26&&parent=
>
>Drew
Yeah, that looks pretty much it. Very close to it. ;-)
Bill Garber from GS-Electronics
Michael J. Mahon
And here's an even better price on it:
http://www.compositevideo.co.uk/product-detail.asp?id=2310&catid=63&manid=95&quantity=1
MdntTrain
>
> - Show quoted text -
Drew, you might want to search the archive here for the old
discussions I started here on similar subjects:
IIgs RGB to VGA experiment
IIgs RGB to YPbPr Component experiment
IIgs RGB to VGA continued
RGB to Component video converter (SCART)
Some of it applies.
JS
Drew
> On Oct 23, 1:37 am, Drew <GoggleD...@gmail.com> wrote:
>
>
>
> > On 23 Oct, 02:05, Steven Hirsch <snhir...@gmail.com> wrote:
>
> > > Christopher G. Mason wrote:
> > > > As for the artifacts, its likely from the upscaling of the video to fit
Thanks for the info. I picked up a CYP CM-345S (which does seem
exactly like the Highway 100 unit) and it all outputted ok using a
Scart cable modified to sync on composite (standard Vintageware seemed
to be stable but picture quality just not as good as sync on
composite). Output (using 1024 by 768) was not bad and is very close
to what i got on Scart onto LCD (Samsung T200HD, but haven't got one
at the moment to really compare). Though i have only tested GS/OS and
a few games. So would recommend the unit if you are after something
acceptable. I managed to pick one of ebay for £46 :-), so not too
costly.
Though I have decided to go down the route of picking up an Amiga
monitor as they do the trick nicely and plenty available in the UK it
seems. LCD is good as backup when the old CRTs finally die :-)
Drew
Steven Hirsch
> Thanks for the info. I picked up a CYP CM-345S (which does seem
> exactly like the Highway 100 unit) and it all outputted ok using a
> Scart cable modified to sync on composite (standard Vintageware seemed
> to be stable but picture quality just not as good as sync on
> composite).
That's what I discovered here as well. Other users (JS/MdntTrain) found that
the stock wiring (mono --> sync, I believe) worked better. Must be some
variation across different IIGS motherboards and/or converter boxes.
> Output (using 1024 by 768) was not bad and is very close
> to what i got on Scart onto LCD (Samsung T200HD, but haven't got one
> at the moment to really compare). Though i have only tested GS/OS and
> a few games. So would recommend the unit if you are after something
> acceptable. I managed to pick one of ebay for £46 :-), so not too
> costly.
Not to mention that 640x480 interlaced NTSC from an Amiga 2000 looks drop-dead
gorgeous through that box. It flickers so badly on a 15Khz. CRT monitor that
I couldn't even look at it without getting a headache.
MdntTrain
I got the best results having the converter output at 640x480 (least
amount of processing), then letting my LCD do the upconversion to it's
native resolution, or better, letting my multisync CRT just slow down
to a natural rate of 640x480. These results might not hold true for
everyone -- just depends on whether their monitor's video handling
exceeds the converter's abilities.
I tried the Amiga monitor approach also, but remember, not only is the
screen really small (too small for my eyes these days), but your video
won't be nearly as nice looking: the other big advantage to the
converter is that you're in 480p mode as opposed to 240p on the Amiga
screen ... meaning, for one, solid colors without missing interlace
lines.
I get the nicest looking results using the coverter into a good CRT
VGA 17" monitor (a Dell/Sony Trinitron in this case). The ideal CRT
would be native 640x480... but I've never found one of those in 17" or
larger.
JS
Drew
> amount of processing), then letting my LCD do the upconversion to it's
> native resolution, or better, letting my multisync CRT just slow down
> to a natural rate of 640x480. These results might not hold true for
> everyone -- just depends on whether their monitor's video handling
> exceeds the converter's abilities.
On my 20 inch Dell widescreen LCD results seem best using Aspect and
1024 by 768 for a larger picture, but if i switch to 1:1 640 seems
best, but not sure if this is just because the picture is smaller. I
wonder if trying a 15inch LCD and running at 640by 480 will be
better...I am sure my work has a spare one ;-)
> I tried the Amiga monitor approach also, but remember, not only is the
> screen really small (too small for my eyes these days), but your video
> won't be nearly as nice looking: the other big advantage to the
> converter is that you're in 480p mode as opposed to 240p on the Amiga
> screen ... meaning, for one, solid colors without missing interlace
> lines.
I know the older amiga (14 inch) screens suffers from larger dot
pitch, but i quite like that retro look :-) and i prefer the overall
look of the picture, seems clearer to me.
> I get the nicest looking results using the coverter into a good CRT
> VGA 17" monitor (a Dell/Sony Trinitron in this case). The ideal CRT
> would be native 640x480... but I've never found one of those in 17" or
> larger.
Must try a VGA CRT as i agree that should be better than LCD.
The pause/blank screen when the converter switches res and my monitor
tries to also sync is a little annoying, when booting my GS i never
see the Apple IIGS bit, just GS/OS loading. I also get a strange
issue in Sierra games when i open the restore/save menu the converter
seems to crash with only showing the top bit of the screen, I have to
power off the converter then back on again and then seems fine, but i
only have to do this once everytime i use the converter....odd.
Cheers
MdntTrain
It's both that the pic is smaller, and because in that configuration,
you're minimizing the amount of processing (extrapolation) on the
video.
<< I wonder if trying a 15inch LCD and running at 640by 480 will be
better...I am sure my work has a spare one ;-) >>
It might. Ideally, an old 640x480 native LCD would theoretically be
best.. but the problem is that older LCD technology isn't very good
compared to the newer. To my eyes, a quality, hi-rez upscaling LCD
(such as my 1280x1024 Samsung 910MP) easily outperforms an older
technology 640x480 LCD, especially in terms of black level and
contrast. I tried it.
<<I know the older amiga (14 inch) screens suffers from larger dot
pitch, but i quite like that retro look :-) and i prefer the overall
look of the picture, seems clearer to me. >>
The larger dot pitch actually helps in this case with the color
dithering... but by 240p and 480p, I wasn't referring to dot pitch...
but interlaced video versus non interlaced (or progressive scan). My
eyes have greedily took to 480p or higher video many years ago, and
they get irritated by blank lines or line jiggle now.
<<The pause/blank screen when the converter switches res and my
monitor
tries to also sync is a little annoying, when booting my GS i never
see the Apple IIGS bit, just GS/OS loading.>>
Yeah, I find that annoying too.. I wondered if it's doing that in
response to the changing dot clocks coming the IIgs as video modes are
switched.. but as its dot sync to the 16mhz super hires mode is
imperfect, I'm actually not sure what it's doing. It could just be
that the V+H syncs coming from the IIgs are interrupted during mode
changes, thus simply requiring the converter to relock onto the
15.7khz signal.
JS
Michael J. Mahon
As you noted, the change in dot clock is a likely cause. When the IIgs
switches to 16MHz (SHR) mode, the lock circuitry that was happy with
14.3MHz becomes unsatisfied, and so disables video and starts to hunt
for a new lock. When it fails to do so, it settles on some sampling
frequency and re-enables video conversion.