| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 137.1 | More and more confused... | PNO::SANDERSB | a belagana | Mon Jun 27 1988 12:49 | 60 |
|
I've some more investigation and have found new information as
well as come up with more questions.
The Zenith ZCM-1490 specifications:
Video in: 0.0 to 0.714V peak to peak
75 ohms, 1V peak to peak max.
Sync in:
Horizontal: 31.49kHz, �1kHz
Vertical: 60Hz to 70 Hz
Mode selection (lines): 350 400 480
Horizontal (TTL): pos. neg. neg.
Vertical (TTL): neg. pos. neg.
70Hz 60Hz 60Hz
Pinout 15-pin D-connector:
1 - Red 10 - Digital/Sync gnd.
2 - Green 11 - Reserved (mode)
3 - Blue 12 - Reserved
5 - Reserved (Test) 13 - Horizantal Sync
6 - Red Gnd 14 - Vertical Sync
7 - Green Gnd
8 - Blue Gnd
Resolution (dots x lines):
640 x 480 Zenith, VGA
640 x 480 MCGA
320 x 200 MCGA
640 x 350 EGA
320 x 200 CGA
720 x 350 MAA
750 x 350 Hercules
As can be seen from the specifications, this monitor can display
all the modes. The problem is that this monitor is not a
multi-mode monitor.
The delima is that I can understand that a scan doubler would be
needed to get the Zentih monitor to work in low res mode with the
ST, I do not understand how the folks using the Sony TV/monitors
and VR241's are able to use medium resolution mode. With the
Horizontal sync frequency doubled, you should be getting 2 scan
lines for each visual line on your screen. The exception to this
is Jeff Lomicka, who should be flipping the horizontal freq.
switch on the back of his "VR241 compatible".
Anybody have any insights on how a monitor with a 15.75kHz
Horizontal sync frequency is able to work with an ST that is
supposed to be putting out a 31.49kHz Horizontal sync frequency?
Bob
|
| 137.2 | horiz. fo. the same for Low + Med | MILRAT::WALLACE | | Mon Jun 27 1988 13:23 | 16 |
| I don't know monitor theory but I do know that I have used a VR241
in both Medium and Low resolution with no problem. There is no
horizantle frequency switch on a VR241!
I don't know how Low and Medium resolution can be two different
horizantal frequencies. In both resolutions you have the same number
of scan lines and the same verticle frequency so the horizontal
frequency must be the same (assumming number of scan lines during
vertical blank stays the same, theres no reason for it to change).
The number of pixels on a scan line changes between medium and low
resolution but that doesn't mean the horizantal frequency changes.
Were did you get your horizontal frequency numbers from?
Ray
|
| 137.3 | | PNO::SANDERSB | a belagana | Mon Jun 27 1988 14:27 | 35 |
| < Note 137.2 by MILRAT::WALLACE >
-< horiz. fo. the same for Low + Med >-
> Were did you get your horizontal frequency numbers from?
From an old issue of Antic (or STart) and looking at Dave
Weaver's note on the NEC Multi-Sync II, along with the sales
fellow at the local Atari outlet here in Phoenix saying that it
was EGA (IBM) compatible. Looking up EGA boards for PC's in the
Heath/Zenith catalog shows that EGA Horiz. sync be:
21.85kHz (EGA)
31.49kHz (EGA+ (also known as VGA))
The local store doesn't have Abacus' ST Internals so I have not
been able to verify what the video output per resolution is.
Adding to all of this is the fact that I have to use a PC based
mag. to determine monitor characteristics, as I have yet to see
any review on monitors in the Atari based publications. Maybe
power without the price also means you get no information...
Does anybody have the actual video output specifications? If so
would you please put them in here, as exactly as possible?
FYI - The May 1988 issue of Personal Computing has both a review
of the top PC monitors and a buyers guide. The prices are all
list, all of the monitors listed can be purchased for less. As
an example - Zenith ZCM-1490, list $999, various adds in the same
magazine has it selling for $649 to $769. The NEC Multisync II
seems to have stablized at $610 (list is $899).
Bob
|
| 137.4 | | LEDS::ACCIARDI | I Blit, therefore I am... | Mon Jun 27 1988 14:40 | 6 |
| I think you'r in error on the med-res horizontal scan rate. I believe
it's 15.75 KHz (hence Sony's can deal with it) not 31.5 KHz.
I once commented that med-res was 31.5 KHz and Jeff corrected me.
Ed.
|
| 137.5 | | PNO::SANDERSB | a belagana | Mon Jun 27 1988 14:44 | 7 |
|
Thanks, it appears that 15.74kHz is the actual freq.
BTW - Jeff's VR241 compatible does has a horiz. freq. switch on
the back. I used to have one like his hooked up to a PRO-350.
Bob
|
| 137.6 | I hope you didn't buy this one yet | PRNSYS::LOMICKAJ | Jeff Lomicka | Mon Jun 27 1988 15:35 | 35 |
| Yes, my color monitor does have a switch, but I never touch it. I
always use it in VR241 mode. Also yes, the horizontal and vertical
sync timings are the same for medium and low resolution. The
difference between medium res and low res on the Atari is the
horizontal BANDWIDTH required to get a clear picture. For low res,
this is approximately 60 frames * 240 scanlines * 320 pixels each, plus
approx. 20% for overscan, for a total of about 5� Mhz - which is just
over broadcast TV gives you, and low enough that you can still read it
on your television. For medium res, there are 640 pixels in a
scanline, requiring about 10 Mhz. This would be permanantly fuzzy on a
TV set.
So, to use a monitor on the Atari, you need a monitor that can accept
sync at the following rates:
Low Res - 15khz horizontal, 60hz vertical, with about 5mhz video bandwidth
Medium Res - 15khz horizontal, 60hz vertical, with about 10mhz video bandwidth
High Res - 34khz horizontal, 70hz vertical, with about 21mhz video bandwidth
It's not clear to me that you can get this monitor to work on the Atari
at all. I looked closely at the numbers and noticed that they all seem
to operate with a horizontal rate of about 31.5 khz. 480 lines at 60
hz is 28khz, 350 lines at 70hz is 24khz. add in a bit for overscan. I
suspect that the 320x200 is a red herring. I think they are doubling
pixels in the controller, trading pixels for colors, and feeding the
video with 640x400 timing. The closest operating mode is to use the
"350" position, where you might be able to get some response out of the
Atari's high-res mode. You can do the 70hz frame rate of High Res, but
you can't do the 480 lines. You only get 350. The Atari will be
throwing scanlines at you at something like 34Khz. That will throw the
timing off.
(Also, there's nothing "standard" about IBM's 15-pin video conector. A
"standard" monitor uses BNC's.)
|
| 137.7 | Well, there are other monitors... | PNO::SANDERSB | a belagana | Mon Jun 27 1988 17:41 | 62 |
|
No I haven't bought the monitor yet. In fact I haven't bought
the ST yet. I'm working on buying a monitor at approx. the same
time as I purchase the ST, only I don't want the Atari monitors
and the Thomson that the local store sells is somewhat lacking in
resolution (I found that it has a .42 dot pitch).
Although you are right about getting this monitor to work with
the ST is a loosing battle, I've got a call into the local Zenith
Technical support person. Somebody has to let them know that
there is more to the world than PC clones and Macs...
For those that are looking for better monitors, here is a list of
the top rated ones the should work on the ST using Dave Weaver's
note as a guideline for wiring.
(This list is in Alphabetical order. All prices are list, they
can be found for less. All monitors have either a .31mm dot
pitch (13" and 14") unless otherwise specified. All monitors are
VGA compatible, meaning there is a D-15 connector cable available
to plug into the controller card.)
Mitsubishi Electronics America, Inc.
AUM1371A - Diamond Scan, $889, Multiscan, 14", 800 by 560
pixels, 30MHz, 15.75kHz - 35kHz horizontal,
45Hz - 75Hz vertical, Text switch,
scan-over/under switch, accepts composite
input.
NEC Home Electronics (U.S.A.) Inc.
Multisync II - $899, Multiscan, 14", 800 by 560 pixels,
30MHz, 15.75kHz to 35kHz horizontal, 50Hz to 80Hz
vertical, Text switch (amber, green, or paper-white),
tilt-swivel base.
Princeton Graphic Systems
Ultrasync - $849, Multiscan, 12", 800 by 600 pixels,
30MHz, 15.75kHz to 35kHz horizontal, 45Hz to 120Hz
vertical, .28mm dot pitch, text switch (green, amber,
cyan, white-on-blue), tilt/swivel base
Sony Corporation of America
CPD-1303 - $825, Multiscan, 13", 800 by 600 pixels,
25MHz, 15.75kHz to 36kHz horizontal, 50Hz to 100Hz
vertical, .37mm aperture-grill dot pitch (Sony says this
is comparable to .31mm shadow-mask dot pitch)
With the exception of the I*M 8513 and Zenith ZCM-1490 (neither
is ST compatible) these are the top rated monitors. They are not
the only ones out there, these are the best at what they do on
I*M PCs and compatibles. If they are good enough for them then
they should be good enough for serious work on any Atari ST or
Mega. In addition you won't need one of those funky monitor
switches. The total cost of a Multiscan monitor will set you
back around $600 plus a cable. It is more than the cost of both
of Ataris monitors and a monitor switch by approx. $100.
Bob
|
| 137.8 | a quick update | PNO::SANDERSB | a belagana | Mon Jun 27 1988 20:52 | 11 |
|
The Zenith Technical support person hadn't the foggiest idea
about changing the Horiz. sync., nor did they know if Zenith was
going to bring out a multiscan version of the monitor.
I looked at a couple of ads in the PC mag and found that most of
the previous monitors could be purchased for between $525 to
$700. The exception to this was Sony, I did not find them
advertised by any dealer.
Bob
|
| 137.9 | All in a nights work.. | PNO::SANDERSB | a belagana | Tue Jun 28 1988 13:52 | 91 |
|
Last night I stopped in at one of the I*M shops close to my home
(AZ Computer Wharehouse for those that are keeping track) and
looked at monitors. I was able to see all of the monitors on the
previous reply except for the Mitsubishi Diamond Scan (they
didn't have it out of the box). What follows is a mini review of
what I saw and my impressions.
NEC Multisync II, $609 - This is one very nice monitor.
The color and picture resolution are almost as good as
the Zenith ZCM-1490. There is some glare even with the
etched glass tube, but that is expected. I forget which
type of PC or clone it was hooked up to, but it was
running in the VGA mode. The text only switch produced
very clear graphics and text with no color fringing in
any of the monochrome settings (amber, green,
paper-white). The User has full control over the
centering, horizontal, and veritical positioning and size
of the picture as well has changing the horizonital
aspect ratio (two position switch). All of this was
available from the front of the monitor! (I wish we
(DEC) had a few of these capabilites.) I didn't notice
any resyncing problems or issues with this monitor.
Princeton Graphic Systems, Ultrasync, $499 - This 12"
monitor was hooked up to a PS/2 pedistial system. The
graphics were outstanding as was the text on this
monitor. Some type of CAD system was also shown with
pulldown menus and different sized fonts. This is the
monitor for someone that will be doing a lot of drafting
work and can't afford a larger (19") monitor. The text
only function was a switch on the side of the monitor and
I did not see any color fringing in the monochrome modes.
The only disadvantage that I was able to see was that
there was considerable blooming on the screen as
different software/modes were selected. This may have
been due to resyncing (most likely) and would not be a
problem unless a lot of system resets are done.
Princeton may be running the Power Supply close to its
limits and resyncing may be drawing a lot of current. It
may also have something to do with the video driver card
in the IBM system.
Sony Corporation of America, CPD-1303, $599 - This monitor
was hooked up to an AT clone. The graphics were very
good, but not quite as good as either the NEC or
Princeton monitors. The Sony does not have either a
glare filter or an Etched glass tube so glare is a real
problem with this monitor. Another problem that was
pointed out was that during resyncing the internal
relay(s) in the Sony can be heard. This could be a minor
irritation to some folks. There was no decernable bloom
when resyncing as with the Princeton monitor. There is
no text only mode on this monitor, which is not really a
big deal.
Although they had a Zenith ZCM-1490, I didn't do any evaluation
of it due to its incompability.
The setups did not allow using the same software to evaluate the
monitors. While this was a disadvantage, it was fairly easy to
tell the overall qualities of each. I still want to look at the
Mitsubishi Diamond Scan and I may go back to the Heath Zenith
Store and look at there ZCM-1390 multiscanning monitor.
As usual when going into foreign teritory I had to explain that I
wanted to hook the monitor up to an Atari ST, then explain what
that was, along with what an Amiga was, along with getting the
"Why don't you buy a real machine" line. The sales person kept
getting the Atari and Amiga confused along with trying to
convince that PCs can do more things better (a demonstration of
Shadow F/X was run, nice package, both the Atari ST and the Amiga
can do better, but it was a good animation package). I didn't
say anything when he showed me Allocade's Test Drive on the AT
clone with the Sony monitor, the graphics were CRUDE (I've
played Test Drive for many hours on my Brother-in-Law's Amiga)
and very low resolution, I don't know if it was the AT, Video
card, or just the limitations of the IBM architechure. Finally I
played a little FS II on an 80286 based clone with the Zenith
ZCM-1490 in VGA graphics mode, what a difference, no jerkiness,
clear graphics.
Rich Amiga owners owe it to themselves to have some fun and start
visiting IBM clone shops with their 80286, 1Mb emulator card
equipped 2000's. Same goes for AtariST owners with MagicSac, go
visit your local Apple Mac shop.
Bob
|
| 137.10 | | LEDS::ACCIARDI | I Blit, therefore I am... | Tue Jun 28 1988 14:30 | 13 |
|
Don't forget that just two years ago, the Mac was a joke toy computer
here in the US. The way it made it into Big Companies was through
the Art departments. Eventually, folks became impressed by it's
ease of use, clear display, and the quality of the software available.
By the way, I have the Princeton Ultrasync connected to my A2000.
I chose it after comparing the Sony and Zenith FTM models. The
Zenith had a mind-bogglingly gorgeous color display, but I rejected
it because of the fixed horizontal scan rate. Too bad, since it's
such a nice beast.
Ed.
|
| 137.11 | | PNO::SANDERSB | a belagana | Tue Jun 28 1988 16:35 | 12 |
|
re -.1: Does your Ultrasync bloom or change size, or does the
Amiga not cause resyncing?
Now that I have thought about it a bit, I want to make a slight
correction to the Princeton Ultrasync - I stated that I thought
the Power Supply was running at the limit. The correct
terminology should be that it appears that the power supply has
poor regulation under heavy load conditions. The Princeton is
still one of the top monitors on the market today.
Bob
|
| 137.12 | Horizontal Sync Frequency | LDP::WEAVER | Laboratory Data Products | Tue Jun 28 1988 19:02 | 16 |
| Re: .0
When I referred to "horizontal bandwidth" I really meant the
"horizontal sync frequency". I hope that helps to clear up
the confusion. The sync frequency is derived by taking
1/sync-pulse-width. The numbers I published in my article
were right out of Atari literature, and may have been their
wording, if I can shift any blame for the misuse of "bandwidth"
(it was probably all my fault). Low rez requires a 15.7KHz
horizontal timing pulse, and Med. rez requires a 31.5KHz timing
pulse. Note the specs I quoted were for the Atari monitors, not
the actual signals coming out of the machine (but one would hope
they match within some reasonable delta).
Sorry for any confusion,
-Dave
|
| 137.13 | display notes.. | LEDS::ACCIARDI | I Blit, therefore I am... | Wed Jun 29 1988 12:34 | 84 |
| Per Bob's request, here's a short review of the Princeton Ultrasync
monitor...
First, I'll digress to explain why I needed an multisync-type monitor.
As you may know, the Amiga offers several basic graphics modes,
as does the ST. The horizontal resolution is either 320 or 640
dots (except in Overscan, which can reach 704 dots) and the verticle
resolution is either 200 or 400 lines (again, 483 lines is available
for video work). In all modes, the horizontal scan rate is 15.75
KHz, unlike the 31.5 Hi-res ST mode that looks so pretty.
One of the Amiga's biggest plusses is also it's biggest flaw, depending
on your application. The 400 line graphics mode is an interlaced
display. This means that 200 even lines are painted in 1/60 of a
second, then 200 odd lines are painted in the next 1/60 of a second;
this means that it takes 1/30 of a second to display a complete frame
rather than 1/60 of a second. This is exactly how television works,
which is why it's a snap to genlock a live video signal to an Amiga
display. Even the system clock is a 2X multiple of the NTSC color
burst frequency. This is fantastic for video work.
Unfortunately, an interlaced display will flicker like mad, depending
on the contrast of the colors used. This is because by the time
the beam finishes painting the last of the odd lines, the even lines
have begun to fade, creating the flicker.
Why not just have a non-interlaced 400 line option like the ST?
It is possible, but as you start adding bit planes (color) the display
will begin to steal clock cycles that would have otherwise been
available to the CPU. Atari avoided the cycle-stealing problem
by only allowing 1 bit plane in 400 line mode. Amiga took the interlace
approach, which allows lots of colors, but flickers annoyingly.
Actually, Amiga also has a second solution to the problem; adding
expansion memory. Expansion memory resides on an entirely different
buss. With expansion memory, there is no contention between memory
that the custom chips need to access and the memory that the CPU
needs to access.
An ideal invention would be a frame buffer that stores the two
interlaced frames in it's own memory, combines them, then bumps
the frequency up. I have such a board in my A2000, but the board
outputs video at 31.5 KHz, hence the need for a better monitor.
CBM is actually working on new monitors that do just that, while
still allowing for NTSC compatibility, since the de-interlacing
is done last. They are also close to releasing the Enhanced Chip
Set, which allows 2 bit planes (4 colors) of non-interlaced hi-res.
Anyway, I looked at the Sony, Zenith and Princeton monitors. I
actually owned a Sony CPD-1290 for my A1000. It was a nice monitor,
but every Sony display I've seen suffers from varying degrees of
'pincushion' where the verticle window borders bow inwards.
The Princeton has no noticible pincushion effect. However, when
sliding custom screens up and down, you can actually see the display
shrink or expand as the monitor struggles to deal with radically
different color pallets on the different screens. Not really annoying,
just curious.
The Princeton also has a button in back that shrinks the display.
This is nice if you want a black border around your display area,
like a VT240.
There is a button on the side that scrolls through various tints
of blue, tan, amber, white and green backgrounds. I don't use this,
since I like my custom desktop colors. (Workbench in Amiga-ese.)
The Princeton has a terrific tilt'n'swivel built in. The display
is 800 x 600 dots, and the dot pitch is .28 mm, tighter than anyone
but Sony at .26 mm. The 12" display is no handicap, since you
are visually presented with more dots/inch than a 13" or 14" monitor.
The old Mac and mono ST trick. Color text actually looks better than
a Mac or mono ST, which is no small feat.
The etched screen does a fine job of reducing glare. The screen
is curved in both planes, as opposed to Sony (curved in one plane)
or Zenith (totally flat) but this isn't a problem. The display
area can be expanded right up to the plastic bezel with no visible
distortion.
I paid $569 for mine, although I've seen mail order prices as low
as $500.
Ed.
|
| 137.14 | A small update | ACE::SANDERS | Doing it with Raw Drivers | Thu Mar 16 1989 09:02 | 13 |
|
The local Atari dealer hear (Plaza Computers in Albuquerque, NM)
tried the Mitsubishi Diamond Scan and couldn't get it to sync in
Hi-Res mode, so watch out for this monitor. I do understand that
it has been used successfully on Amigas.
The Princeton MAX-15 can be used on the Atari in all three modes
with the addition of a bit of active circuitry (a buffer between
the RGB outputs and the monitor) and floating the ground signal
1V above actual ground. The MAX-15 is a 15-inch monochrome
monitor with both RBG(I) and TTL inputs.
Bob
|
| 137.15 | | NEWOA::BAILEY | I promise, R = S | Sat Jan 04 1992 15:11 | 7 |
|
Two questions about monitors
(1) Is there some way of using a VT220 as a mono monitor?
(2) If I have a colour monitor that works fine with a VGA PC..
will that work on an Atari ?
|