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Commodore 128 and 80 Colums

stangman517

Experienced Member
Joined
Dec 15, 2014
Messages
213
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
 

AdamAnt316

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May 23, 2016
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Location
Massachusetts
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
 

gertk

Experienced Member
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Jan 26, 2016
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398
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Netherlands
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.
 

stangman517

Experienced Member
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Dec 15, 2014
Messages
213
Location
Georgia, USA
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!!!
 

stangman517

Experienced Member
Joined
Dec 15, 2014
Messages
213
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Georgia, USA
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!
 

gertk

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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.
 

billdeg

Technician
Joined
Nov 18, 2003
Messages
3,872
Location
Landenberg, PA USA
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
 
Last edited:

RobertB

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Mar 20, 2006
Messages
836
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Visalia, California
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
 

billdeg

Technician
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Nov 18, 2003
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Landenberg, PA USA
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..
 

KC9UDX

Space Commander
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Lutenblag
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.
 

RobertB

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gsteemso

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Sep 28, 2008
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north of Seattle, USA
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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