Jump to content
Sign in to follow this  
DistantStar001

What color is your VIC-20 Screen Boarder?

Recommended Posts

So, recently I've been piecing together what would have been my second VIC-20 (now going to be my third).  It's just the mother board (two-prong), absent the socketed IC's.  

 

Now here's the thing.  I own two other VIC-20's, and both of these machines give a very blue border.  Not the teal usual teal color that I typically see in YouTube videos or VICE.  Since both machines work, and have never given even a hint of graphical glitching, I just figured that it was an NTSC vs PAL thing, or maybe it was the cameras or screens that they were using.  Honestly, I never put too much thought into it, as I was just happy that they worked.  

 

Now as I mentioned, the Motherboard was missing all of its socketed IC's, including the VIC chip.  So I got a new old-stock 6560 with a date code for the 50th week of 1982, and salvaged a 6502 from an un-enhanced //e.  So now I have everything except the ROMs (VIA's are on the way).  I decided to transplant the ROMs from my one of the other machines, just to see if the board would boot.  And it did!!!  But this is where things got interesting for me.   I noticed that the border color was different than my other two machines.  It's teal!

 

976505978_ScreenShot2020-12-25at4_06_12PM.thumb.png.03687bd95e29f6df932342e4a228b75d.png

 

After consulting on some of the people on Denial, I was informed to that the teal boarder was "more normal", and that I could make adjust the video with the trimmer pots in the VIC cage (not sure what it's actually called).  No go.  I could make the picture brighter or darker, monochrome, black or color.  So then I swapped the VIC's and the teal border followed the new chip.  

 

Looking at the date codes, I noticed that both of the blue boarder VIC's were older than my 'new' chip.  One's form 1981.  The other is a 1982 chip, but from the 32 week.  

 

So this has me wondering if anyone else has noticed this?  Is this a sign of age and usage?  Or is this a manufacturing difference for later VIC's?  Do PAL 6561 VIC's have the same issues?  Thoughts...  Observations... This really has me curious!?!  :D 

Share this post


Link to post
Share on other sites

All the VIC's I've seen produce a cyan colour that is more teal than light blue. As noted you should be able to adjust the pots for lightness and saturation, but perhaps the second one doesn't work or you trimmed it too far to lose all colour. I've gone through a number of PAL and at least one NTSC VIC-20 and all display the expected colours - NTSC of course dependent on a monitor/TV that supports its colour encoding.

Share this post


Link to post
Share on other sites
9 minutes ago, carlsson said:

All the VIC's I've seen produce a cyan colour that is more teal than light blue. As noted you should be able to adjust the pots for lightness and saturation, but perhaps the second one doesn't work or you trimmed it too far to lose all colour. I've gone through a number of PAL and at least one NTSC VIC-20 and all display the expected colours - NTSC of course dependent on a monitor/TV that supports its colour encoding.

Interesting.  I tried adjusting the pots on both of the 'blue screen' VIC's with no effect on the border color.  Brightness and saturation, but not color tint.  The thing is, the the text color appears to be right on all three.  It's only the border color that's different.  The only thing that changed the border on the 'blue VIC's' was swapping chips.  All I did was swap chips and suddenly my 'blue VIC' was teal.  

 

Out of curiosity, what are the date codes on these machines?  My current hypothesis is that there was a modification or refinement to the design of the VIC chip in 1982 that continued through the rest of the line.  If I'm correct, then all VIC chips manufactured before a certain date should produce a blue boarder, while later ones give the customary teal.  

 

I'm kinda shaky on my usage and age hypothesies, since one of the 'blue VIC's' show only minimal signs of use.  But not knowing the history of the machine, I can't rule it out completely.  If someone has a heavily used machine with chips manufactured after the 50th week of 82, then that would demonstrate that use and age are factors, rather than a change in chip design/manufacture.

Share this post


Link to post
Share on other sites

OK! New information!  This is definitely a tint issue.  I adjusted the tint on my screen.  A red shift on a blue VIC corrects to a teal screen, where a green shift makes a 'teal VIC' go blue.  

 

From what I understand, this phenomenon should be limited to NTSC machines.  Since, to the best of my knowledge, PAL signals don't require tint adjustments the in the same way that NTSC machines do.  

 

Unfortunately, this does little for me to narrow down the possibilities.  Without age, usage or manufacture data, there's no way for me to narrow my hypotheses.  Still...  Getting closer.

Share this post


Link to post
Share on other sites

OK. I just got finished with a VIC. Black screen so my first thing was to change the VIC chip. Turns out that it was the BASIC ROM. The interesting thing was, when I got it working, the "new" VIC chip (from China) displayed Blue not Teal. I switched back to the original VIC chip and it was a proper teal. I did no further testing with the blue VIC chip.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...