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C64 - A reappraisal 2017


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#351 Heaven/TQA OFFLINE  

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Posted Tue Feb 27, 2018 4:09 PM

But, if you chose only the color for a picture use, you never could use the 16 colors together, except you like strange color settings. Not to forget that the colors changes 3 times on the C64. The colors themselves were not the point, but they changed the brightness of the colors. Which means, if you create a game on a C64 2 , it may look wishy-washy on a C64 of the 1st generation.


Interesting if thats true... regarding VIC revisions like
SID.

But colors. Yeah at first months you miss the 256 palette.... (or 128) but when you realize that you can set those 16 for free in a 8x8 it becomes a dream on itself knowing the out of the box 4 col or 5 col of A8.

Did not yet do scrolling which is a pain and unused for me
To copy memory around with the slower 6502 and even at some point color ram, too.... but as history showed the scrolling even done by cpu does not prevent running games on C64 in 50/60 fps thanks to the damned sprites ;)

#352 VladR OFFLINE  

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Posted Tue Feb 27, 2018 8:53 PM

 
 Yeah, I was a Jag developer for a short while. It was an ambitious design slaughtered by the need to keep it all really cheap (and by insufficient hardware testing). Even though you could do some fast things with it, nobody in the game industry has got the time to figure out how to squeeze every last ounce of performance out of a complicated architecture. Especially if the docs are sparse.

Cool. Did you work on some commercial game at the brief active jaguar period ? Or was it recent ?

 

 

Well, when you saddle a 6502 with a screen that big you've got two problems:

 

1. Most of your RAM will be consumed with graphics. Double buffering will consume all of it.

2. It's slow to update large bitmaps with a slow processor. This is one of the things that hurt the Apple IIgs. It had modes like an ST, but couldn't draw anywhere near as fast.

Then I guess it's good that Eclaire can run at 28 MHz :)

 

Atari as it should have been...



#353 carlsson OFFLINE  

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Posted Wed Feb 28, 2018 1:45 AM

The early VIC-II chip has five levels of luminosity. If you turn down saturation, these colours should display the same in B&W:

 

* Black

* Dark grey, red, blue, brown (4)

* Middle grey, purple, green, orange, pink, light blue (6)

* Light grey, cyan, yellow, light green (4)

* White

 

Newer versions of the VIC-II has nine levels of luminosity:

 

* Black

* Blue, brown

* Dark grey, red

* Purple, orange

* Middle grey, light blue

* Green, pink

* Light grey, cyan

* Yellow, light green

* White

 

This will to some degree affect how you perceive colour pictures depending on VIC-II version.

 

The math behind the VIC-II colours: http://unusedino.de/...vic656x/colors/

How to use flicker tricks to mimic more colours: http://www.aaronbell...e-commodore-64/



#354 emkay OFFLINE  

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Posted Wed Feb 28, 2018 2:04 AM

The early VIC-II chip has five levels of luminosity. If you turn down saturation, these colours should display the same in B&W:
 
* Black
* Dark grey, red, blue, brown (4)
* Middle grey, purple, green, orange, pink, light blue (6)
* Light grey, cyan, yellow, light green (4)
* White
 
Newer versions of the VIC-II has nine levels of luminosity:
 
* Black
* Blue, brown
* Dark grey, red
* Purple, orange
* Middle grey, light blue
* Green, pink
* Light grey, cyan
* Yellow, light green
* White
 
This will to some degree affect how you perceive colour pictures depending on VIC-II version.


Actually it brings more "colors" to a b/w monitor.
There haven't been changes in the 1st version , already? Didn't TMR mention this change after a year of the 1st release ?
And there is a lot of C64 Art existing, using 5 , 7 and up to 11 brightness values. Possibly calculation errors by the software... hmmm

#355 carlsson OFFLINE  

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Posted Wed Feb 28, 2018 2:28 AM

Not sure. All the references I can find point to 5 or 9 levels. The very early C64 only output composite video through a 5-pin DIN, but I think the palette and luminosities stayed for longer. I used to have a breadbin with 8-pin DIN but the five levels of luminosities.

 

Here are two more links on the same topic:

http://www.pepto.de/projects/colorvic/

https://ilesj.wordpr...color-blending/

 

Anyway, the argument would be that if you can't be certain exactly which four colours the user will see on the screen, it is better to program so it only displays two colours and hope those will be deterministic, than using a higher colour resolution and risk that it looks like sh!t on certain computers or monitors.



#356 Heaven/TQA OFFLINE  

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Posted Wed Feb 28, 2018 2:46 AM

9 levels of lum vs 5 is huge difference... so my c64C has 9? while a lot breadbins have only 5?



#357 carlsson OFFLINE  

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Posted Wed Feb 28, 2018 2:55 AM

Yes, something like that. Exactly which chip revision the change occurred, I haven't looked up.



#358 landgraf OFFLINE  

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Posted Wed Feb 28, 2018 5:40 AM

IIRC the R1 revision is the only one with just 5 luma levels, at least when it comes to PAL VICs. On the plus side it comes in a nice ceramic package, though. :)



#359 TMR OFFLINE  

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Posted Wed Feb 28, 2018 5:44 AM

9 levels of lum vs 5 is huge difference... so my c64C has 9? while a lot breadbins have only 5?


i wouldn't have said "a lot of breadbins" personally, i've only ever seen one example of five luminances in the wild which was a "l@@k r4r3" surprisingly low serial PAL machine which came in for repair. There might be slightly more machines still in service over in NTSC Land though, but it's still small numbers.

#360 Heaven/TQA OFFLINE  

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Posted Wed Feb 28, 2018 6:48 AM

ok. so nothing I need to take care.



#361 carlsson OFFLINE  

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Posted Wed Feb 28, 2018 7:03 AM

My old "L@@K R4R3" breadbin (5 levels of luminosities, old board though no Silver Label) was repurposed into a modded C64 with dual SID, built in LCD screen and spray painted black... I thought it was broken for 15++ years until I tried a different PSU and found that it still was working 100%. I never quite understood that it was so uncommon though. I am quite convinced it had a 8-pin video output though, but the more I think about it, the less sure I am.



#362 Mclaneinc OFFLINE  

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Posted Wed Feb 28, 2018 7:10 AM

Doesn't it?

 

I thought it did...I used to make up the leads while I was at Maplin, mind you, they are going in to administration as I type..



#363 landgraf OFFLINE  

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Posted Wed Feb 28, 2018 7:23 AM

I never quite understood that it was so uncommon though. I am quite convinced it had a 8-pin video output though, but the more I think about it, the less sure I am.

For what it's worth, I have a breadbin with an Assy 250407 type mainboard (with 8-pin AV) and an R1 VIC installed by factory. This mainboard type was produced somewhen between 1982 and 1984 and is also the last board that reportedly contained the buggy R2 Kernal occasionally (mine has an R3 Kernal, though).

 

My guess would therefore be that those are boards where C= used up next to all of the older chips they still had in stock, at the time the 250425 board came out they only had later VIC- and Kernal-revisions left.



#364 carlsson OFFLINE  

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Posted Wed Feb 28, 2018 7:27 AM

Oh yes. I keep forgetting that Commodore used to install whichever parts they had at hand, and that assembly might depend on which factory, which person, which phase of the moon was present when it was assembled. Perhaps that is part of what gives Commodore a bad reputation on build quality, the uneven supply of parts, sockets, that barely two computers manufactured the same week would be identical. It could also be a reason why they were able to cut costs, less quality assurance.



#365 Mclaneinc OFFLINE  

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Posted Wed Feb 28, 2018 7:41 AM

Possibly the origin of the term "Cheap as Chips" :)






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