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Commodore 128 and 80 Colums

stangman517

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Dec 15, 2014
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243
Location
Georgia, USA
Greetings all.

Just bought a C128, and the introduction guide says to get 80 columns an RGBI monitor is needed. I have two - haven't tried them because I don't want it in my computer room; takes up too much space. Is there an alternative? I have a TV/monitor; will this work? It has component and VGA connections? Or is there a DB9 converter that will work and then hook it up to a VGA LCD.

Thanks
 
If you're handy with a soldering iron, perhaps you could try building one of the circuits on this page:

https://sites.google.com/site/h2obsession/CBM/C128/rgbi-to-vga

There's also the RGBI video DAC board sold on this site:

http://www.bit-c-128.com/

Both of these pages mention the Gonbes GBS-8200 and GBS-8220 video converters. I don't know anything off-hand about these units, but they're apparently available from various sources. Good luck!
-Adam
 
If you don't need color you can use the monochrome output on the DB9 connector and hook it up to the Y connector of your YUV input. That will give a crisp output in greyshades.
A simple DB9 connector with a coaxial cable ending in a CINCH connector will do.
You can try and use the CVBS input of yor monitor/TV too but I found out there is much HF noise on the monochrome output and some monitors/TV's interpret it as color information making the display unreadable.
 
I made contact with the creator of the board/system, and will probably buy what he's got. To use the C128 on a VGA monitor is awesome!

Thank you very much for your response AdamAnt316!!!

His prices are very reasonable!!!
 
Yeah I've been breaking out some of my old cables/etc to see what I can test with but with caution anyway. It's amazing to find out just how much STUFF a collector has when breaking out boxes of stuff hanging around the house!!!! ;-)

Thanks for your ideas!
 
Even though you can generate 640x240 lines (or even 480 with interlace) on the RGB output you are still left with rather huge borders when using a RGB(I) to VGA converter. It would be nice to have a 1:1 pixel mapping on a VGA display (on a 800x600 display for example) or borderless on a 1280x960 for example. The sharpness/clarity would be much better.
 
For the record a 1084 is a perfect fit if you can find one. I have a C128D in my office with this monitor. I use cables from both video ports on the computer into different video in ports of the 1084. When I need 80 column mode I set the RGB (CVBS) button found on the 1084's front panel to the OUT position. On the C128 I set the 40/80 col key to the IN position.

When I want 40-col mode I have the opposite - RGB (CVBS) In, 40/80 col key out.

You have to reboot/reset to switch back and forth.

I would try to find a 1084 or similar monitor that has the two video modes and two sets of output ports. Otherwise with the VGA solution, wouldn't one need a switchbox to simulate both types of video ports' signals? Perhaps a switch box would give you the ability to switch output cables going to different ports. I did not check the VGA adapter solution mentioned above, perhaps there is a simpler solution.

Here is the system I am referring to
http://vintagecomputer.net/pictures/2016/C-128-workstation.jpg

Bill
 
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Otherwise with the VGA solution, wouldn't one need a switchbox to simulate both types of video ports' signals? Perhaps a switch box would give you the ability to switch output cables going to different ports.
Very true. A VGA switchbox with 2 VGA inputs and 1 VGA output. You would need a composite/s-video-to-VGA adapter, in addition to the BIT-C128 digital RGB-to-VGA adapter.

Tired from walking around Victoria, B.C.,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm
July 30-31 Commodore Vegas Expo v12 -
http://www.portcommodore.com/commvex
 
so, if you want both modes, wouldn't you recommend picking up a 1084 or similar display rather than a VGA? There are a few 1084's on ebay right now. I can only speak specifically for the 1084 without the "S" (don't know about the 1084-S). I would get a 1084 to be safe, I don't recall if the S model also works this way..
 
My memory is vague, but I owned a dozen or so 1084 monitors at one point. It seems to me that there were multiple variations of 1084 and 1084S, which were all different.
 
Just out of curiosity, why would you need to reset the machine when you want to switch between 40- and 80-column display modes? There's a BASIC 7 command for that (GRAPHIC); for syntax details see the Commodore BASIC Encyclopedia (I think it was on Hydrophilic's site?) Did you know that the 128 can be run dual-head (using both screens at once)? It's built in to the way it works that it be kinda-sorta straightforward to switch which screen is active.
 
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