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Testa
Account closed
Registered: Oct 2004
Posts: 197 |
fetch the 0-sprite. with open borders...
hi,
ik have a little problem.. i want to open the sideborders with the 4 lowest sprites... i have two questions about it..
when i do the D016 write i use a dec d016 or a lsr or ror as opcode... why does a sty, sta, stx not work....
has it something to do with cpu takeover cycles at that point...
second question... what to do on a badline....
there are not enough free cycles. with 4 sprites for a inc, ror or lsr d016 instead of a sta, sty or stx...
i realize it is common knowledge.. but sorry i dont. know it...
bye...
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Oswald
Registered: Apr 2002
Posts: 5022 |
Quote: Quote:AFAIK atari just stops the CPU when needed, no questions asked.
yes, exactly. and on the c64 the cpu can still perform non-write cycles (if any) until it really stops.
no, I mean on the c64 you have this 3 cycle zone, while atari does not have this. AFAIK. tried to google, but not much on this behaviour, I remember reading somewhere that they simply stopped with the clock line (before sally!), but dunno how they solved the bus business. |
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chatGPZ
Registered: Dec 2001
Posts: 11133 |
Quote:no, I mean on the c64 you have this 3 cycle zone, while atari does not have this.
it should be there too, but unlike its done in the c64, they used a much simplier approach to implement it, and halt the cpu regardless if it could still perfom the read cycles or not.
the whole thing becomes even more interesting if expansionport action comes into play too.... =D |
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Oswald
Registered: Apr 2002
Posts: 5022 |
i dont get it, could you explain it in depth ? including expansion port :)
(c64 cpu is stopped on first read cycle, how can it be more simpler than that?:) |
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AlexC
Registered: Jan 2008
Posts: 293 |
Quote: But it's fun still to see people trying... in somewhat like 2010!
Don't you know that c64 is all about making impossible things a reality ;) That is why we love this machine so much. |
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chatGPZ
Registered: Dec 2001
Posts: 11133 |
Quote:could you explain it in depth ? including expansion port :)
sorry, no, that'd be a bit too much =P (and i cant say i really fully understand it either, i am not a hardware guy :))
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Oswald
Registered: Apr 2002
Posts: 5022 |
Quote: Quote:could you explain it in depth ? including expansion port :)
sorry, no, that'd be a bit too much =P (and i cant say i really fully understand it either, i am not a hardware guy :))
translation: "I'm rambling about something I dont understand myself" |
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chatGPZ
Registered: Dec 2001
Posts: 11133 |
i understand enough of it to look up the information i need - but certainly not enough to explain it to someone else in great detail. even more so to someone who doesnt already fully understand the relatively simple vic bus takeover =P |
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Oswald
Registered: Apr 2002
Posts: 5022 |
you're playing mr smartass, but the end of the day you're only an arrogant asshole. C64 mechanism can be explained in a sentence or two , you claim atari is even simpler -BUT- now you dont want to explain because that would take too much time. You're simply ridiculous. It's crystal clear you have no idea whatsoever. |
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chatGPZ
Registered: Dec 2001
Posts: 11133 |
ofcourse, mr. i can't code sideborder =) |
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Oswald
Registered: Apr 2002
Posts: 5022 |
ofcourse I cant. btw the problem with the expansions port IIRC that it doesnt have signals like clock. |
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