Update: Added GDM 1960 info courtesy of Henrique Miranda (hmiranda@inescn.pt)
Update: Added a success with HP98752A (19" trinitron, OEM'd from Sony)
And I finally got a new home for this page (this is it!)
After days of work, I finally have a huge (19.2" viewable) monitor on my desk displaying a quite sharp 1280x1024 image under Linux, WinNT and Win95, all at the price of $6.
Making a fixed-sync monitor work on a standard VGA card is surprisingly simple, once you know what to do. And if you happen to have a SONY GDM-1961 or any of its incarnations such as the DEC VRT 19-HA (and some HP monitors I believe), this page could help you see the bigger picture, literally.
Although my expereiences are with the GDM 1961, other sync-on green monitors would probably work just as well, if you can get hold of the technical specifications. Typical for sync-on-greens, they have 3 BNC connectors at the back. Others might have a separate composite sync (4 BNCs) or separate Horizontal and Vertical sync (5 BNCs). The more BNCs the better/easier it is, as you won't have to do any hacks to merge the sync signal with the green signal. I will here describe the 3 BNC sync on green solution that is needed for the GDM 1961.
Some monitors, such as the GDM-1960, is possible to modify so that it can accept composite sync, which most graphics cards can output. See section 3b for making modifications to the monitor.
NOTE: I take no responsibility for any injury or damage caused by any of the ideas presented here. Proceed at your own risk.
OK? Here's what you have to do:
However, I sent request to com.sys.dec, and Mike Thompson was kind enough to give me all the details I needed to know (along with a few extra):
There is more than one version of the VRT19 VRT19-DA (aka SONY GDM-1960) VRT19-D3 (aka SONY GDM-1960) VRT19-D4 VRT19-HA (aka SONY GDM-1961) VRT19-H4 Following are the specs from two different DEC manuals, yes the specs listed are different. >From the DEC manual EK-VRT19-TC-001 (12/91) VRT19-DA/D4 operates at 66 Hz VRT19-HA/H4 operates at 66 or 72 Hz .... Specifications for the VRT 19-HA (AKA SONY GDM-1961): Display Resolution: 1280x1024 Pixel CLock 130Mhz Horizonital Horiz Freq: 77.1728 Khz Active Video: 9.7853 us (1280 pixels) Back Porch: 1712.4 ns (224 pixels) Blanking Interval: 3.1802 us (416 pixels) Front Porch: 244.6 ns (32 pixels) Horizontal Period: 12.9656 us (1696 pixels) Sync Pulse: 1223.2 ns (160 pixels) Vertical Vert Freq: 72.5562 Hz Active Video: 13.2768 ms Blanking Interval: 39 horizontal lines Front Porch: 3 horizontal lines Sync Pulse: 3 horizontal lines Vertical Period: 13.7824 ms Power Consumption: 220 watts maximum From the DEC manual ER-VRT19-OP-002, for VRT19-DA, D3, D4: Resolution: 1280x1024 Video Bandwidth: 100 Mhz Pixel Clock: 119.843 Mhz Horizonital Horiz Freq: 70.7Khz Active Video: 10.68 ns Back Porch: 1873 ns Blanking Interval: 3.465 ms Front Porch: 258 ns Sync Pulse: 1335 ns Vertical Vert Freq: 66.5 Hz Active Video: 14.485 ms Blanking Interval: 39 horizontal lines Front Porch: 3 horizontal lines Sync Pulse: 3 horizontal lines Vertical Period: 15.035 msThe following specs for the GDM-1960 came from Henrique Miranda (hmiranda@inescn.pt)
Resolution: 1280x1024 Video Bandwidth: 100 MHz Pixel Clock: 119.843 MHz Horizontal Horiz Freq: 70.7 kHz Active Video: 10.68 ns Back Porch: 1873 ns Blanking Interval: 3.465 ms Front Porch: 258 ns Sync Pulse: 1335 ns Vertical Vert Freq: 66.5 Hz Active Video: 14.485 ms Blanking Interval: 39 horizontal lines Front Porch: 3 horizontal lines Sync Pulse: 3 horizontal lines Vertical Period: 15.035 ms
Another good source of monitor information is http://hawks.ha.md.us/hardware/monitor.html. However, you will not find all you need there, so you probably have to do some experimentation to get a good picture.
Also, check if your card can produce a sync on green signal. If it can, all you have to do is to connect the videocard to the monitor, and select the correct resolution. But beware! My Matrox Mystique has this ability, but NO DRIVERS support it! So why (oh why?) does Matrox list sync on green as "optional" when they don't want to make drivers that support it?
I believe the Matrox Millennium and a few "older" high-end cards may support this, in particular under XFree.
This tip came from Adam Megacz:
As a public service, I just want to let everybody know that the Matrox
Millenium DOES NOT need extra hardware to do sync-on-green; it is an
undocumented, unsupported feature that Texas Instruments put onto their
RamDac chip which Matrox wishes didn't exist -- but it does. (Matrox buys
their RamDac from Texas Instruments).
Below are the directions for Linux and Win95. Please do not email me
asking for help; I don't have time to do tech-support. This information is
provided with NO WARRANTY. I assume NO RESPONSIBILITY for whatever the
heck happens. I will be putting up further documentation on
http://www.andrew.cmu.edu/~megacz/ as soon as I get a chance.
Directions:
Linux/Xfree86:
In the XF86Config file (on Debian systems this is /etc/X11/XF86Config),
insert the line
Option "sync_on_green"
Example:
Section "Device"
Identifier "My Video Card"
VendorName "Unknown"
BoardName "Unknown"
Option "sync_on_green"
EndSection
Win95 (possibly NT; untested)
In the mga.mon file (search your hard drive for it), you need to add 32
to the H_SYNC_POL line; normally the register is one bit wide (0 or 1).
I found that if you include values greater than 1, it will roll over
into the sync-on-green register and flip it to sync-on-green mode.
Here is the sample setting that I use for my NeXT Megapixel 21" Color
monitor (bought it for $99! What a steal!):
[*Next_Monitor_@76Hz_(1024x768X8.Z1)]
PIXEL_CLK = 90000
H_DISP = 1024
H_FPORCH = 88
H_SYNC = 136
H_BPORCH = 184
H_SYNC_POL = 32
V_DISP = 768
V_FPORCH = 3
V_SYNC = 6
V_BPORCH = 21
V_SYNC_POL = 0
INTERLACE_ENABLE = 0
Note: I have tried this with my Mystique, but so far with no luck. Does anyone
have more information regarding this?
This came from Craig Kline [craigk@mail.utexas.edu]:
I've had success making an HP98752A (19" trinitron, OEM'd from Sony) monitor work with my matrox millinium 2 card without a sync on green adapter and in win95. I added these to the mga.mon file in their proper places: [HP.98752A Fixed Freq 19"] 640X480 = NA 800X600 = NA 1024X768 = NA 1152X864 = NA 1280X1024 = NI, *HPFIXEDMON@76 1600X1200 = NA [*HPFIXEDMON@76] PIXEL_CLK = 112000 H_DISP = 1280 H_FPORCH = 32 H_SYNC = 193 H_BPORCH = 224 H_SYNC_POL = 32 V_DISP = 1024 V_FPORCH = 3 V_SYNC = 3 V_BPORCH = 36 V_SYNC_POL = 1 INTERLACE_ENABLE = 0The following is a Linux modeline for a modified GDM-1960 (See section 3b):
# 1280x1024@66.5 Hz, Hsync=70.7 kHz Modeline "GDM1960-1280x1024" 119.843 1280 1312 1472 1696 1024 1027 1030 1069 +hsync -vsync
Note: Some monitors susch as the GDM-1960 can be modified so that they accept composite sync. This is a better solution than making your own sync on green adapter. See section 3b.
I used the circuit described in the Apollo sync on green FAQ.
I used:
1 4066 (it looks like 4, but it is 4 on one chip)
1 Adjustable resistor (I use 1-20 Ohm)
1 XOR Gate
1 VGA-connector to the GFX board
1 Connector to the BNC cable
Also, I pull the +5v Vcc from the RED cable on the Drive B disk-drive power-cable.
NOTE: There are several designs out there with XORs, ORs, XNORs etc. Most of those will probably work, but you will have to adjust the polarity of the Horizontal and Vertical sync signals. I use XOR with +Hsync and -Vsync.
NOTE2: I noticed a big difference in picture quality when I switched to thin coax-cables for the R, G and B instead of the "normal" thin wires. Also, keep them as short as possible (I use 5 cm).
If you have a GDM 1960, you can make an even easier modification to the monitor. This tip came from Paul Langemeijer:
A thing I might add to the problem of the sync-on-green, is the 'modifying' of your monitor. well actually it isn't that hard. If you screw of some panels (the one near the connectors)(with the monitor turned of). I found holes for two more bnc connectors. you can put them in, attach a bridge and put in two resistors (the holes for these are obvious, the numbers are above them). and you've got a 5-BNC monitor (and it works).Additional comments came from Paul: You should use 80 Ohm resistors, and the 1960 syncs perfectly to 1024*768@85 (Standard VESA videomode).
This section is submitted by Henrique Miranda (hmiranda@inescn.pt).
+-----------------------------------------------------------------------+
| Adding External Syncs to Sony GDM-1960 Monitor |
| |
| Henrique Miranda (hmiranda@inescn.pt) |
+-----------------------------------------------------------------------+
In order to add external vertical and horizontal sync signals to the
GDM-1960 (aka VRT19-D3), I performed the following steps:
Note: I take no responsibility for any damage or injury caused by any
of these procedures. Proceed at your own risk.
1. Make sure the monitor is unplugged. Unscrew the four cover screws and
then take the cover off.
2. Unscrew two more. These hold the BNC panel.
3. There are another two small black screws that hold the BNC panel to the
PCB that should be taken off too.
4. In that PCB you will find four unused BNC holes. Those aligned with the
RGB Video In are your Hsync (PCB reference: J-604) and Vsync (PCB
reference: J-605) signal inputs.
5. Solder two 82 Ohm resistors at R607 and R608. Add a jumper at position
JW601. Also solder two small jumpers connecting both center pads of
J-609 and J-610.
6. Screw two female BNCs (panel type) over J-604 an J-605 and solder them
to the corresponding center pads.
7. Drill two 13mm diameter holes in the BNC panel, allowing the two new
BNCs to pass trough this panel.
8. Finally, cover your monitor et voila! You have an excellent monitor
that you can attach to any graphics card capable of generating the
appropriate timing. The video signal specs of the GDM-1960 are:
Resolution: 1280x1024
Video Bandwidth: 100 MHz
Pixel Clock: 119.843 MHz
Horizontal
Horiz Freq: 70.7 kHz
Active Video: 10.68 ns
Back Porch: 1873 ns
Blanking Interval: 3.465 ms
Front Porch: 258 ns
Sync Pulse: 1335 ns
Vertical
Vert Freq: 66.5 Hz
Active Video: 14.485 ms
Blanking Interval: 39 horizontal lines
Front Porch: 3 horizontal lines
Sync Pulse: 3 horizontal lines
Vertical Period: 15.035 ms
Here is the Modeline that I use in my Linux box:
# 1280x1024@66.5 Hz, Hsync=70.7 kHz
Modeline "GDM1960-1280x1024" 119.843 1280 1312 1472 1696 1024 1027 1030
1069 +hsync -vsync
You can also use this monitor under Micro$oft Windoze. All you need
is to install a program that can program your graphics card to the
mode described above. SCITECH Display Doctor program
(http://www.scitechsoft.com) proved to handle this easily.
This is my XFree86 Modeline:
# 1280x1024@72.5Hz, Hsync=77.1kHz Modeline "1280x1024" 130 1280 1300 1460 1696 1024 1027 1030 1069 +hsync -vsyncFor users of other monitors, I would recommend the automatic Modeline Calculation Table
If you use a commercial X-server, you might want to take a look at this page to convert the modelines into something even more obscure.
For Win96 and NT, I made a new monitor definition in the MGA.MON file that comes with the Matrox Mystique driver.
;; Put this in the Monitors section [Sony.GDM-1961] 640X480 = NA 800X600 = NA 1024X768 = NA 1152X864 = NA 1280X1024 = NI, *Sony_GDM-1961_(1280X1024X8.Z1) 1280X1024.Z1 = NI, *Sony_GDM-1961_(1280X1024X8.Z1) 1280X1024.Z2 = NA 1280X1024.Z4 = NA 1600X1200 = NA NTSC = NA PAL = NA ;; And this one in the screen-resolutions section [*Sony_GDM-1961_(1280X1024X8.Z1)] PIXEL_CLK = 130000 H_DISP = 1280 H_FPORCH = 32 H_SYNC = 160 H_BPORCH = 224 H_SYNC_POL = 1 V_DISP = 1024 V_FPORCH = 3 V_SYNC = 3 V_BPORCH = 39 V_SYNC_POL = 0 INTERLACE_ENABLE = 0
Note: I have noticed that BOTH Win95 AND NT may crash when they want to switch to a lower non-existing resolution (screensavers etc), so you might want to add some VGA-resolutions to this monitor definition. You won't be able to see them on your monitor, but you could always reconnect your old monitor to have a look. OR: You could tweak your monitor to display the lower resolutions! Have a look at section 6.
NOTE: USE A PLASTIC SCREWDRIVER! On the GDM-1961, I found one on the inside of the cover. The insides of a monitor may give you 20-30.000 Volts worth of shock, so be advised. Use your head, not your metal screwdriver (and I don't mean that literally :-)
These modes involve a _lot_ of tweaking, and I doubt the modelines I came to will work for you. Consider them as an example. When you push the monitor to the limits of its specifications things start to depend on temperature and monitor tuning (see section 5). But you should be able to reduce the resolutins significantly a little by little.
Follow this (X11 only):
1. Reduce the visible display area with 50 pixels horizantally and vertically by editing the
modeline. This way
Modeline "1280x1024" 130 1280 1300 1460 1696 1024 1027 1030 1069 +hsync -vsyncbecomes
Modeline "1230x974" 130 1230 1300 1460 1696 974 1027 1030 1069 +hsync -vsync
You might try larger reductions, but it is important to make the adjustments so small that the resulting image is still useable.
2. Now adjust the resulting image with xvidtune, stabilizing it.
3. Take the new stabilized modeline, reduce the visible area, and repeat until you reach the desired resolution.
This way you end up with a smaller image with large front and back porches (large areas of black on both sides of the picture). How low resolution you get depends on how flexible your monitor is when it comes to the vertical refresh rate. To make it show 640x480 the screen had to refresh at 87Hz, wich is a bit above the specifications. The 1961 also have automatic dual scan, and I believe the low-scan mode is necessary to reach the lowest resolutions.
This is my new modelines under X11:
Modeline "1280x1024" 130 1280 1300 1460 1696 1024 1027 1030 1069 +hsync -vsync Modeline "640x480" 130.00 640 944 1104 1632 480 727 730 917 +hsync -vsync Modeline "800x600" 130.00 800 804 964 1784 600 743 746 849 +hsync -vsyncThis is my new monitor definition under NT and Win95:
640X480 = NI, *Gateway_"Sony"_GDM-1961_(640X480X8.Z1) 800X600 = NI, *Gateway_"Sony"_GDM-1961_(800X600X8.Z1) 1024X768 = NA 1152X864 = NA 1280X1024 = NI, *Gateway_"Sony"_GDM-1961_(1280X1024X8.Z1) 1280X1024.Z1 = NI, *Gateway_"Sony"_GDM-1961_(1280X1024X8.Z1) 1280X1024.Z2 = NA 1280X1024.Z4 = NA 1600X1200 = NA NTSC = NA PAL = NA [*Gateway_"Sony"_GDM-1961_(1280X1024X8.Z1)] PIXEL_CLK = 130000 H_DISP = 1280 H_FPORCH = 32 H_SYNC = 160 H_BPORCH = 224 H_SYNC_POL = 1 V_DISP = 1024 V_FPORCH = 3 V_SYNC = 3 V_BPORCH = 39 V_SYNC_POL = 0 INTERLACE_ENABLE = 0 [*Gateway_"Sony"_GDM-1961_(800X600X8.Z1)] PIXEL_CLK = 130000 H_DISP = 800 H_FPORCH = 272 H_SYNC = 160 H_BPORCH = 484 H_SYNC_POL = 1 V_DISP = 600 V_FPORCH = 63 V_SYNC = 3 V_BPORCH = 315 V_SYNC_POL = 0 INTERLACE_ENABLE = 0 [*Gateway_"Sony"_GDM-1961_(640X480X8.Z1)] PIXEL_CLK = 130000 H_DISP = 640 H_FPORCH = 304 H_SYNC = 160 H_BPORCH = 528 H_SYNC_POL = 1 V_DISP = 480 V_FPORCH = 247 V_SYNC = 3 V_BPORCH = 197 V_SYNC_POL = 0 INTERLACE_ENABLE = 0
Not the similarities between the MGA.mon file and the modelines. In general you can convert between the two this way:
Modeline "1280x1024" 130 1280 1312 1452 1676 1024 1027 1030 1069 +hsync -vsync H_DISP = 1280 = 1280 + H_FPORCH = 32 = 1312 + H_SYNC = 160 = 1452 + H_BPORCH = 224 = 1676 H_SYNC_POL = 1 = +hsync V_DISP = 1024 = 1024 + V_FPORCH = 3 = 1027 + V_SYNC = 3 = 1030 + V_BPORCH = 39 = 1069 V_SYNC_POL = 0 = -vsync
Viloa! A complete modeline!
Note that my modelines above doesn't follow this rule completely, but the difference is the result of additional tweaking under WinNT.
It won't work. The part of the gfx card that displays text is separate from the gfx engine, and is not capable of a clockspeed of more than 70mhz, not the required 130 mhz. (This, ofcourse depends on your gfx card) Stupid? Yes, but then PC hardware seems to be more based on old workarounds than common sense.
Your mileage might vary, but I haven't heard of anyone able to overclock the textengine that much. BTW, the "lower resolutins" I describe won't help, as they still use the same clock frequency (wich is why they work on a fixed sync monitor in the first place).
This info came from Jay Gramlich:
I wanted to let you know though that SVGA textmodes will work with some cards My S3Trio can do 80x25 with some fiddling. My S3 Virge can't get there though I can make it work in something like 64x25 (An old 864 could get some great modes!) I do think that the author of SVGATextMode says that Matrox's (and many newer cards) aren't capable of high textmodes clocks though.
Q: But my GFX card driver doesn't have its own MGA.mon configuration file! How can I alter the Windows monitor definitions instead?
I have absolutely no idea, but if you figure it out, do tell me! (It can't be _that_ difficult, have a look at the installation programs that come with a new monitor.)