which monitor has high resolution?

[Bob Myers]

Well, actually going much below 60 doesn't really
work all that well on most LCDs.

The popular [mis]conception among those who have
thought about it, but not read your book , is that LCD
panels are a form of write-only frame buffer. You send
a data set to a pixel triad, and it stays at that value
until you send another data set, whenever.

You're right, it IS more complicated than that. The
LCD is only a sort-of "frame buffer"; it's closer to being a
very large (physically, at least) and oddly analog form of
dynamic write-only memory. As such, it DOES need to
be refreshed periodically, and there are other limitations
regarding how fast (and how slow, oddly enough) the
panel electronics (the timing controller, or "TCON," and
drivers) can be run. There have been LCDs made which
operate more slowly than 50 or 60 Hz, and there are certainly
those which operate much more rapidly - but typically in
a monitor, the panel itself is running very close to 60 Hz,
just as a sort of de-facto standard.

Is there usually/sometimes/never a real frame buffer
in that path? If present, it "should" completely decouple
what the panel needs from what the host wants to send.

There is very often - I won't say "always," because there
are always exception - a real frame buffer, and even
sometimes a double buffer, because of the need for the
monitor "front end" to be able to support frame-rate
conversiion in order to handle input rates other than
60 Hz. So most often the actual displayed frame rate IS
decoupled from the input rate, unless the input rate is
within the panel's native timing range. Which is another
reason to be running an LCD monitor at its native or
"preferred" timing, always.

Which makes it less likely than ever that avoiding dual-link
will be accomplished by using low host frame rates.

No, avoiding dual-link DVI for such things as the 30"
2560 x 1600 monitors is going to be achieved only by
switching to one of the newer, faster digital interfaces, such
as HDMI 1.3 or (more likely in the PC workd)
DisplayPort.

The other work-around gimmick that is even less likely is
data reduction (e.g. sending only changed pixels).

Yes, but that trick (generically referred to as "conditional
updating" won't work with any interface that doesn't support
the passing of address information, etc., within the image.
That requires a packetized communications protocol, most
likely, and that means the only real hope we have for getting
to the "conditional update" mode will be DisplayPort. Both
of the other common digital interfaces (DVI, HDMI) are
basically just delivering a normal raster-scan video stream in
digital form instead of analog. The initial release of DisplayPort
doesn't fully take advantage of the packetized protocol either,
and so far doesn't support that mode, but it is expected to be
added in a future upgrade of the standard.

Bob M.

 

[Bob Myers]

Short answer is "hardly ever"... Only added if it is considered
necessary to the business to support different frame rates
(like content intended for film, at 24 Hz multiples). Us
"integrators" tend to follow instructions given by our (direct)
customers (solutions providers), and allow the solutions providers
to deal with the end user issues.... Not very pretty, but not much
choice either.

I'm going to clarify my last response, because "NGA"
and I aren't really disagreeing. He's right in that there is
hardly ever a separate frame buffer block in the monitor
"front end" - however, the scaler/controller IC very commonly
does implement sufficient internal memory so as to enable
frame-rate conversion. A full frame's worth of, say, 1600
x 1200 video is only a little more than 5 MB, and you
can pretty easily tuck enough memory into such ICs to
handle the FRC chore. If an LCD advertises coverage of,
say, the usual 75 Hz or 85 Hz CRT-style video timings, then
it is almost certainly performing frame-rate conversion in order
to drive the LCD within its native timing range. If it's just
a 60 Hz sort of device - and there certainly are a lot of LCD
prducts out there that DO only work over a very limited timing
range - then no, it's got no need for the extra cost burden of
supporting frame-rate conversion.

Absolutely they do skimp - if you think PC margins are slim,
the margins on peripherals are smaller ... pennies make a
difference.

And those of us in the systems business most certainly are
always putting the thumbscrews on you guys in the peripherals
business when it comes to cost...

I often say that the panel makers are the only ones making
any profit at all, and even that is largely supposition, since they
do so well at keeping their financials disguised. The only concrete
clue is that they are still in business.......

Yeah, and SOMEONE is willing to keep plowing billions of
dollars (well, these days, mostly won and NT$ ) into those
nice big new fabs...

Bob M.

 

[Eldorage]

1920 on a 19in is 119 dpi, which is well beyond the 100 dpi
threshold of "unusable" for Windows users, due to assumptions
made by Mr.Bill long ago, and hard-coded into too many
legacy apps, icons, bit-mapped system fonts, etc.

1920 is also as high as single-link DVI can go without
tricks that no one wants to use so far. Tolerable LCDs
with dual-link just only hit the market two weeks ago.
See the "what's the deal at 30in 2560" thread here.

Consequently, the market for large >100 dpi tends to be fairly
specialized, is way above 100 dpi, and is always at least dual-link.

Many a 17-inch laptop can be configured with 1920x1200 on its built-in
screen. Try configuring one at dell.com for example.

If my calculations are correct, that's 133 dpi. Same as the LCD I am staring
at now, which is a 15-inch Thinkpad at 1600x1200.

 

[Del Rio]

Currently using a Dell Inspiron E1705 that has a 1920x1200
19" (diagonal) display. I'd like to buy a 22" or 23"
flat-panel computer monitor that has no less pixel density

Q: have you actually tried out a 22" or 23" display at 1920x1200,
and found it inadequate?

 

[Not Gimpy Anymore]

(ship)

I'm going to clarify my last response, because "NGA"
and I aren't really disagreeing. He's right in that there is
hardly ever a separate frame buffer block in the monitor
"front end" - however, the scaler/controller IC very commonly
does implement sufficient internal memory so as to enable
frame-rate conversion. A full frame's worth of, say, 1600
x 1200 video is only a little more than 5 MB, and you
can pretty easily tuck enough memory into such ICs to
handle the FRC chore. If an LCD advertises coverage of,
say, the usual 75 Hz or 85 Hz CRT-style video timings, then
it is almost certainly performing frame-rate conversion in order
to drive the LCD within its native timing range. If it's just
a 60 Hz sort of device - and there certainly are a lot of LCD
prducts out there that DO only work over a very limited timing
range - then no, it's got no need for the extra cost burden of
supporting frame-rate conversion.

Hey - Glad we can not disagree so much!!! Just wanted to
try & give input from the "penny ante" side of the business... Heh
Don't get to check in here very often - dang customers seem so
demanding these days....

And those of us in the systems business most certainly are
always putting the thumbscrews on you guys in the peripherals
business when it comes to cost...

Yup - 'n we feel the pain.... Maybe we're just masochistic???

Yeah, and SOMEONE is willing to keep plowing billions of
dollars (well, these days, mostly won and NT$ ) into those
nice big new fabs...

Make that won & NT$ & Yuan...... but that's our little secret.....

Bob M.

Always good to hear from you Bob!

NGA

 

[Bob Myers]

Make that won & NT$ & Yuan...... but that's our little secret.....

Well, I was talking about the module fabs, but yeah, more and
more of those are planned for the...ummm....BIGGER China,
aren't they?

That's OK...I kinda like Shanghai....

Bob M.