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Oswald
Registered: Apr 2002
Posts: 5028 |
why not 39 column mode ?
if hiding 1 row is enough for doing vertical scrolling why do we have 38 column mode for horizontal scrollin, why not 39 ?
(and besides anyone can give me a simple random generator ? register readouts doesnt count) |
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enthusi
Registered: May 2004
Posts: 675 |
Its probably 'safe' to feed the seed with rasterposition or some other less random value - I guess.
On the other hand this asl/eor-method annoys the crap out of me when it comes to shuffles in mp3/cd-players. I'm pretty certain they use something alike, and the resulting sequence (rather than random series) is all BUT well well distributed. |
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WVL
Registered: Mar 2002
Posts: 886 |
Quote: about 39 column mode... ;-)
I guess you can't have 39 column mode, because of the length of a clockcycle...
One cc takes as long as the width of one character. To enable 39 column mode (to draw the borders in place) you would have the VIC interrupt inside of one cc (half cc timing) to turn on and off the border...
I guess that wouldn't go well with the timing of the 6510.
:)
Or am I just stoned again? :-D
I guess you're stoned again ;) because you could simply don't expand the borders on either left or right side.. And why does the VIC care about clock-cycles anyway? it has a higher frequency than the cpu, how else can it draw nice pixels? :) |
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Oswald
Registered: Apr 2002
Posts: 5028 |
ok so back to topic guys, anyone has a good guess why is it NOT 39 column mode ? :) |
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
Quote: I guess you're stoned again ;) because you could simply don't expand the borders on either left or right side.. And why does the VIC care about clock-cycles anyway? it has a higher frequency than the cpu, how else can it draw nice pixels? :)
About the stoned... you could be right ;-D
But about the rest... :)
If you don't split a CC halfways, the screen won't be centered anymore... You have one border smaller than the other one.
And the VIC must care, coz the CPU must be halted. And I don't think that would go well in the middle of a CC.
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Devia
Registered: Oct 2004
Posts: 401 |
The border is already one and a half char wider on the left side as it is?! |
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Oswald
Registered: Apr 2002
Posts: 5028 |
Quote: The border is already one and a half char wider on the left side as it is?!
 |
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MRT
Account closed
Registered: Sep 2005
Posts: 149 |
Quote: The border is already one and a half char wider on the left side as it is?!
oi? |
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H.O
Account closed
Registered: Oct 2002
Posts: 70 |
Ok. I'll admit to not having coded much for the c64 in 20 years, and it's been over a year since I last wrote a single line of 6510 code.
But, isnt the 38 (rather then 39) columns based on the idea that you dont know whether the user wants to scroll things in from the left or the right?
Or am I missing something here?
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cadaver
Registered: Feb 2002
Posts: 1154 |
But same could be said that you don't know whether the user wants to scroll in things from the top or the bottom, still it works fine as it is :) |
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Devia
Registered: Oct 2004
Posts: 401 |
@MRT & Oswald: Have you been in emu-land for too long? You have 6 chars on the left and about 4½ chars on the right (404 pixels in total from left to right).
When setting 38 column mode, the border ends 7 pixels further in on the left side and it starts 9 pixels before on the right. So if we had a 39 column mode we probably wouldn't be able to open the side border >8-O
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