nichols+@andrew.cmu.edu (David Nichols) (03/08/89)
A few weeks ago, I posted some questions about VGA boards and monitors.
Here is a summary of the replies that I got. I'll start with my
interpretation of the answers, and follow up with the replies themselves
(edited some). Some of my information comes from a discussion with a local
hardware wizard.
Q: I'm interested in lots of text lines (50+). Some of the boards advertise
60-line modes while some only claim 43-lines. Yet I have seen references by
some writers to the "50-line mode that all VGA boards support." What's the
scoop here? My guess is that the modes the manufacturers advertise are the
BIOS modes, and that any of the boards can be set into 50-line or so modes by
appropriate setting of the VGA registers (at least for the register-
compatible cards). Is this guess correct?
A: Yes. Many programs know how to get to 43 line EGA mode without much BIOS
help. For the rest, you're on your own.
Q: My current favorites for monitors are the Nec Multisync II and the Sony
1302. Both are advertised as handling 560 lines. What happens when you
flip your board into 800x600 mode? Do 40 lines get trashed? Does it work
at all? Or does everything work fine because the monitor specs are
conservative?
A: The basic answer is that either it syncs and you're fine, or it doesn't
sync. If it syncs and you're missing a few lines, tweaking the vertical size
and position pots should do the trick (though you may have to take off the
cover on some monitors). The reason is that the monitor is driving the beams
when the the sync pulses tell it to. If it syncs at all, it should be doing
the right thing. Another possible failure mode is that the horizontal or
vertical retrace can't finish in time before the new data starts arriving
(the "back porch" is too small). This could cause the front of a line to be
wrapped or the top few lines to be lost or distorted.
Q: I thought someone mentioned in this group that the Sony 1302 was great,
but avoid the 1302A. Why? According to the Sony person I talked to, the
difference is that the 1302A has vertical auto-sizing circuitry added, which
seems like a win to me.
A: One person wrote that the 1302A added autosizing and was designed to work
well on a Mac. Another noted that the 1302A he's seen don't work at higher
resolutions even though the 1302 handled them with some grunting.
The edited replies follow. Some of the information conflicts with what I've
said above, so believe whatever you want.
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Date: Thu, 26 Jan 89 19:07:48 EST
From: simon@E.MS.UKY.EDU (Simon Gales)
Organization: U of Kentucky, Mathematical Sciences
lotsa_lines - ega (normally 640x350 graphics) can do 25, 35, and 43 lines
- vga (normally 640x480 graphics) is same as ega plus a 60
line mode.
My Mitsubishi DiamondScan (about $450, multiscan + ntsc) can do 800x600,
but it is rated at 800x560.
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Date: Fri, 27 Jan 89 07:51:13 -0500 (EST)
From: "Johnny J. Chin" <jc58+@andrew.cmu.edu>
Organization: Carnegie-Mellon University
According to what I know, VGA's support 50 lines of text. I'm not sure about
the 60 lines (haven't heard of it before now). Anyway, I can tell you that
at 50 lines, the text is very small and may seem hard to read.
As for the 560 scan lines, you're correct. If you have a card that goes to
800 x 600 mode, there will be 40 lines thrown away. In order to use that
card effectively you must get a higher resolution monitor. If I remember
correctly, Sony and Nec, both have higher resolution monitors. And I think
that the Nec Multisync II has about 640 lines of resolution (vertical) and not
the 560 that you mentioned (I may be very wrong though.)
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Date: Fri, 27 Jan 89 13:32:14 est
From: Steve Corbin <encore!pinocchio!corbin@talcott.harvard.edu>
Organization: Encore Computer Corp, Marlboro, MA
I have a NEC Multisync II. I just recently purchased it and expected it to
work in 800x600 mode. However, it doesn't. It will only do up to 560 lines.
Apparantly the horizontal sync rate is not high enough for 600 lines.
The first 40 lines of the display in 800x600 are chopped off at the top.
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Date: Fri, 27 Jan 89 14:13:26 PST
From: teg@orc.olivetti.com (Tom Griner)
The 50 line mode supported by "all" VGA's is accomplished by changing
the font. You can load in any font into RAM to be used by the VGA
- There are a few public domain programs (vfont, vga50, ...) that can
use small fonts for 43, 50 and 66 lines. Anything more than 50 lines
look terrible because the fonts are too small. On EGA's it is common
to swap the standard 8x14 font with the on board CGA 8x8 font and get
80x43 lines...
I have a Sony CPD 1302 and Mitsubishi Diamond Scan. Both can handle
800x600 generated by my Genoa Super EGA and Video-7 VRAM VGA. Sony
advertises max of 900x560..., but you can go to 600 lines if you have
less than 900 columns... Most 800x600 cards make sure than the monitor
can handle the "bandwidth" by refresshing at only 56 Hertz instead of
60 Hertz. This yields a more "flickery" picture in the 800x600 mode.
I find that I get better looking images in the 640x480 modes.
The dots on the Mitsubishi monitor (and NECs...) are big enough that
in 800x600 mode, two side by side adressed points end up hitting the
same phosphor dot on the screen (so 800x600 resolution is sort of wasted
by the monitor). The Sony has small enough dots to work well in 800x600...
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Date: Sat, 28 Jan 89 18:08:04 -0500 (EST)
From: David Nichols <nichols+@andrew.cmu.edu>
Thanks for the message. Is your Sony the 1302 or the 1302A?
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Date: Sun, 29 Jan 89 18:31:53 PST
From: teg@orc.olivetti.com (Tom Griner)
My Sony is the older CPD1302... I like it alot, but I have found that some
people just don't like the trinitron image. With the very precise stripe
mask picture tube, and one-gun technology you can see definate black stripes
inbetween colors if you are using only one of the phosphor stripes. Ie: if
you have a solid red, green or blue image on the screen. Sony trinitron
monitors have been the number one choice for professional video (ie: used at
networks, tv stations...) because their monitors always turn up at the top
when tested with video measurement machinery... But just because on paper
they are the best monitor doesn't mean that everyone likes them. Here are
some other gripes that I have heard: The high pitched flyback whine (some
people never notice this...) is said to be worse with trinitron's than most
others; The one-gun technology tends to have a problem where white images on
the left of the screen have a bluish tinge, and on the right a redish tinge;
The whites are always too bluish. I just stated all these gripes just to be
fair... I love the monitor, and think it is great, but like I said - some
people find something that they don't like about em.
About the 1302 and 1302A... Apple's color monitor that they sell with the
MACII is actually a modified sony CPD1302. When the MACII came out people
started trying to use CPD1302's on them (because the real Apple trinitron
monitor was in short supply). They found that the CPD1302 didn't look quite
as good as the Apple version, so Sony released the 1302A with some of the
circuitry that the Apple monitor had (that optimized it for the Apple color
cards 640x480 with 66 hertz refresh).
Right now my CPD1302 is connected to a frame grabber board that has 512x512
with 32768 colors. The frame grabber board has an EGA pass trough port with
a Genoa Super EGA 800x600 card in it. Normally the frame grabber converts
the EGA to analog and passes it through to the monitor (I use the Genoa's
100x75 text mode). Then if I run the frame grabber software the board
switches to live digitized video that I can capture (from cable TV tuner,
laser disk player, ...). All this is done by software with no switches to
reset!
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Date: Mon, 30 Jan 89 07:24:16 PST
From: Tom Almy <toma@tekgvs.labs.tek.com>
Organization: Tektronix, Inc., Beaverton, OR.
1. Yes
2. For Multisync, at least, 800x600 works fine.
3. Don't know.
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Date: 30 Jan 89 16:39:34 GMT
From: everett@hpcvlx.HP.COM (Everett Kaser)
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Yes, 60 lines is entirely possible. I've seen it. No, it's NOT real comfort-
able to read. VGA has 480 lines vertically; hence, if you load an 8x8 bit
font, voila! you have 60 lines of text.
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Date: 28 Jan 89 15:53:00 GMT
From: mcdonald@uxe.cso.uiuc.edu
[Replying to Johnny Chin's message on the Multisync II]
The specs say 560 vertical. But it works fine vertically in 600x800
mode. But the horizontal width is too narrow by about one inch.
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Date: 30 Jan 89 18:05:21 GMT
From: ncsmith@ndsuvax.UUCP (Timothy Smith)
Organization: North Dakota State University, Fargo
[Also replying to Chin.]
The NEC Multisync II is capable of being driven to 1024x768, if you don't
mind a little magnetic interference. If you do drive it to 800x600 you will
have to use to horizontal adjustment control to move the picture into the
display area. Also there are no lines thrown away. The card that I am using
is the STB VGA Extra/EM.
===========================================================================
Date: 31 Jan 89 23:44:45 GMT
From: corbin@pinocchio.Encore.COM (Steve Corbin)
Organization: Encore Computer Corp, Marlboro, MA
[Followup to Chin and mcdonald.]
Hmmmm. I have a NEC Multisync II and it doesn't do 560 lines. The top 40
lines in 800x600 mode are chopped off. I have no problems with the horizontal
resolution.
The NEC Multisync 2 A will do 600 lines according to NEC's advertisements.
Apparently the 2 A just came out and I bought the II a few months ago. I
wish I had waited.
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Date: Tue, 31 Jan 89 23:14 CST
From: chasm@killer.Dallas.TX.US (Charles Marslett)
(1) All VGAs can be put into a 50-line text mode (just issue the set-mode
function, then select the 8x8 font with resizing the screen format -- I forget
the exact code, but AH is either 10 or 12 hex). Some VGAs will simplify this
by letting you just pick another mode number. This is more significant if
you want a 720x480 resolution text mode -- that is 60-line 8x9 font text --
then you need to go ding on the registers if a new mode is not provided.
43-line modes are based on the EGA and look rather funky if you do not
put the VGA into an EGA resolution first. Again, some VGAs will make this
easier by having a 43-line mode.
(2) Theoretically the monitors will loose sync with the higher preformance
cards (since they horizontal frequency is too high) or with the lower performance
cards (since the vertical frequency is too low) -- but I have never seen it
happen! Both the Multisync II and the Sony 1303 work fine (and the Sony
1302 is spec'ed to do 800x600 if I recall correctly). The Multisync II/A
is now spec'ed to handle a low refresh rate 800x600, but the faster cards
will give you less flicker at the expense of a minor adjustment to center the
screen when you go into/out of the high res mode.
(3) The only thing you lose with autosizing circuitry on the Sony 1302A
is that the 1302 did a pretty good job of handling 960x720 and 1024x768
resolution screens (even though way out of spec), but for some reason the
1302A does not -- based on a sample of 4 or 5 monitors ;^)! But I cannot
imagine any reason to not go with the 1302A if you do not want to push the
screen to 1024x768 or so. VGA screens are much easier to use when you do
not have to be forever adjusting the vertical size!
---------------------------------------------------------------------------
Date: 3 Mar 89 13:14:20 GMT
From: chasm@killer.DALLAS.TX.US (Charles Marslett)
Organization: The Unix(R) Connection, Dallas, Texas
[Marslett also replied to someone else's similar question.]
The 800x560 specification means that if you put a screen up you will have
to go out of specification on either the horizontal or the vertical timing
to get an 800x600 screen image. That means that (1) if it fails to do 800x600
the monitor will lose sync and either roll vertically or tear horizontally, and
(2) if it does maintain sync, it probably will not have any problems with the
loss of scan lines.
Most card vendors (STB, whom I work for, Orchid, Video 7, Techmar, etc.) provide
support for the most critical of the 800x560 monitors by having an 800x600 mode
that runs at about 56 Hz vertical refresh rate and 35+ KHz horizontal scan
rate. This is just within spec on both timings for the original Multisync
from NEC. For the more critical users with better (more flexible) monitors,
we also support a 60 Hz (flicker free, so called) display with a scan rate
around 37 KHz. It complicates the issue, but it makes more people happy to
have both modes.
So flicker is the main issue, and support of a 36 or 37 KHz horizontal
frequency is the main requirement to provide a 60 Hz 800x600 display. If the
monitor will do that (I think the Multisync 2a is not supposed to, but it
works well with our card, and the Sony and some others do specify support
of such operation).
===========================================================================
Date: Mon, 30 Jan 89 10:30:27 EST
From: hoqax!twb@att.att.com
Organization: AT&T Quality Assurance Center, Holmdel, NJ
PC Magazine July, 1988 tested 9 VGA boards.
===========================================================================
Date: 11 Feb 89 06:54:25 GMT
From: davidg@janus.uucp (David Gaertner)
Organization: XCF, University of California, Berkeley
I've tried the Multisync 2A in 800x600 mode with Microsoft Windows.
With a Vega VGA card, there is a lot of flicker that makes it
unusable. But with a Paradise VGA Plus card, it looked great! Only
the grays looked like they were being affected by some kind of
interference.
===========================================================================
Date: 11 Feb 89 16:57:00 GMT
From: sac90286@uxa.cso.uiuc.edu
If your Multisync 2A flockers in 800x600 mode with your Vega VGA, get a
Princeton UltraSync. No problems in any of the Vega VGA's modes.
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