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Old Fixed-Sync Monitors under Linux?
Hautis asks: "I read somewhere that it should be possible to use huge, old
fixed-sync monitors with any (*vga) video card under Linux,
once you tell XFree86 the exact sync ranges or whatever values
it needs. I happen to have a couple of old VAXen, that is, VAXstations, lying around in my family's cellar. 19 inch mono and RGB tubes, fixed sync. What kind of cables would I need (I can solder well enough)? Would I be able to use text modes also, would a frame buffer beneeded for this? What about (S)VGAlib? Can I have two graphics
adapters, one conn't to my crappy old 15-inch and one to the
huge ancient particle accelerator? Or should I switch between the displays when I want to use X? Will I get a cancer for staying up nights surrounded by 80's display technology?"
There's a FAQ at
http://www.devo.com/video/
I used an old DEC monitor for a couple of
years a while back. It worked fine. You basically
have two options
1. Buy a video card specially made for fixed
frequency monitors
2. Fiddle with your X config so that it runs
at the frequency the monitor wants.
Option #2 is nice because it's free and works
well, though ordinary text modes don't work.
The main problem you're likely to have is that
many fixed frequency monitors have 3 BNC connectors and expect sync signals mixed in with green. You can build a simple circuit to deal
with this. Fiddling with X timings is tiring but
eventually you get there.
Matthias
Don't know about cancer but if you need to be able to use the monitors with textmode SVGATextMode can help you. It lets you set the scan rates while running text mode. And gives you much better text mode too.
As for cables... Many old monitors used RGB cables. Here is the pinouts for your standard SVGA connector:
You probably want to connect the red, green and blue cables to the red video, green video and blue video. The inside pin will be the video. The outside "shield" is the ground. Connect the ground to the analog grounds. The monitor ID pins are unused. The sync pins shouldn't be needed for a fixed frequency monitor.
If this works good! Otherwise don't sue me, I've never tried this before.
As for cancer. Just don't smoke.
I had occasion to do this with an old 19" mono Vax monitor and a 21" IBM 6091. Both served me well, but the lack of console-mode eventually drove me to abandon them. The hardest part will be finding specific specs on your monitors so you can compute the dot clocks. Here are two useful links on the subject. http://www.faqs.org/faqs/pc-har dware-faq/video/part4/ http://www.mindspring.com/~nunez/info /monitor
Fixed sync isn't a problem, all you have to do is find a good modeline (and for text mode, use fb or svgatextmode). But, most of these monitors are nastier - composite sync or sync-on-green. Then you'll have to find a video board that supports these sync modes, or build an adaptor. These are the links I found:
One of these pages claims that the MACH64 can work with my monitor, but I have a VLB one and it doesn't (the modelines given in the page give me "illegal mode according to MACH BIOS" or something). I'll try to exchange it for a PCI. Otherwise, if anyone can send me more modes I'll be very grateful :-)
I have a G200 that I use with a NeXT (Hitachi) 21" monitor. I bought a fixed frequency card from Software Integrators but the X support for Sync On Green is not there. I tried the Matrox and it works great with X, but I dont use (or have) any console modes at all. Interestingly enough the SI card wokrs great in my NT box. There's a site here with good information on fixed freq monitors out there. Since I have two machines that will talk to the NeXT monitor I hooked up a KVM switch (Belkin OmniCube) so I can browse between the two of them. I still keep an old multisync hooked up A/B though for console mode on the Linux box. I dont know how many KVM's will work right with sync on green, but mine does not have a problem.
Good Luck...
-Rich
Ok, I can't really say a lot that wasn't already here. However, I have an old 16" Sun (Sony) monitor that I wanted to use. I did much research and came to a final decision. I'll start at the beginning.
:-)*
Google was great for giving me the information I needed. One big problem is that there is no one page that tells you everything or has links to everything.
So here's some stuff:
Special video cards (good ones, recent acceleration technology) are available. They're more expensive than regular cards, but you're pretty much guaranteed that they'll work. They are specially designed to display text modes on those monitors, which is a huge plus.
Here's a link:
http://www.si87.com/
There are more companies. A search will find them quickly. I remember seeing one that used S3 chipsets. A good thing because they're very supported. Many of these companies explicitly state Linux support. That's another good thing.
If you want to use a regular video card, be mindful of the specs on your monitor. I found an exellent source of monitor data here. There are DEC fixed frequency monitors in there, among many, many more.
If you have sync-on-green, you probably have 3 BNC connectors on the back of your monitor. Any Matrox card will drive this. There's a "sync-on-green" option in the XF86Config file for that. VGA-to-BNC cables can be bought fairly cheaply.
If you have composite sync, you probably have either four BNC connectors or a 13W3 connector (3 large coax pins and 10 regular pins). Don't bother looking for a bare connector to make a cable with. It's a very special kind of cable due to the mixture of coax and regular multiconductor cable. If you want to hack an existing cable (or just buy one to go straight) IBM sells them for US$27.00 compared to everyone else (including Sun) that sells them for ~US$80.00.
ATI cards support composite sync. It's an option in the XF86Config file.
To do composite sync on any other card, you can build a little logic circuit, but I *really* don't recommend that because 13W3 cables are relatively hard to hack, plus you'll get a lot of signal loss. For the price of a card you don't have to screw with, it's worth it.
Having looked at these options, I looked at what came with the monitor: a very old pizzabox Sun 3/80. I only wanted an Xterminal anyway and there is some software called XKernel that turns an old Sun into one. Get it here.
This is the option I'm going with. No major screwing around, plus I get what I want. I bought a cheap ethernet transceiver from D-Link (I had to slice off some of the plastic on the back of my Sun to get it to fit), and I am now waiting for my 13W3 cable to come in from IBM Canada (It *is* a special order, after all).
These old Sun's are easy to find, and tend to have very nice monitors on them. I saw a couple of old Sparcs here for sale for ~CAN$50 each. You can't beat that. They had monitor cables too.
So that's my little experience. It's not exactly tuned to the question, but I'm sure there are many others (I *KNOW* there are) that are watching this question with interest.