Subject: Re: [stella] RESPx and player positions From: bwmott@xxxxxxxxxxxxxx Date: Thu, 23 Apr 1998 14:25:29 -0400 (EDT) |
> It might be possible, that the TIA finishes it's setup routine already > at cycle 22, since cycle 23 ends one pixel in the display. > > This would explain the stange gun position in Atlantis. The > RESPx might end at cycle 22, which would be 2 pixels before > display time. If we add the strange 5 pixel offset, the gun > would be at pixel 3. The HMOVE of 3 pixels to the left, that > you mentioned, would put the gun right at pixel 1. I did a trace of Atlantis to see how it's positioning P0 for the gun on the left side of the screen and here it is: PC=160b IR=85 <$nn 2 0 STA > A=c0 X=ff Y= 8 PS=e5 SP=ff Cyc=14584 PC=160d IR=85 <$nn 10 0 STA > A=c0 X=ff Y= 8 PS=e5 SP=ff Cyc=14587 PC=160f IR=88 <implied 0 0 DEY > A=c0 X=ff Y= 7 PS=65 SP=ff Cyc=14589 PC=1610 IR=10 <implied 0 0 BPL > A=c0 X=ff Y= 7 PS=65 SP=ff Cyc=14592 PC=160f IR=88 <implied 0 0 DEY > A=c0 X=ff Y= 6 PS=65 SP=ff Cyc=14594 PC=1610 IR=10 <implied 0 0 BPL > A=c0 X=ff Y= 6 PS=65 SP=ff Cyc=14597 PC=160f IR=88 <implied 0 0 DEY > A=c0 X=ff Y= 5 PS=65 SP=ff Cyc=14599 PC=1610 IR=10 <implied 0 0 BPL > A=c0 X=ff Y= 5 PS=65 SP=ff Cyc=14602 PC=160f IR=88 <implied 0 0 DEY > A=c0 X=ff Y= 4 PS=65 SP=ff Cyc=14604 PC=1610 IR=10 <implied 0 0 BPL > A=c0 X=ff Y= 4 PS=65 SP=ff Cyc=14607 PC=160f IR=88 <implied 0 0 DEY > A=c0 X=ff Y= 3 PS=65 SP=ff Cyc=14609 PC=1610 IR=10 <implied 0 0 BPL > A=c0 X=ff Y= 3 PS=65 SP=ff Cyc=14612 PC=160f IR=88 <implied 0 0 DEY > A=c0 X=ff Y= 2 PS=65 SP=ff Cyc=14614 PC=1610 IR=10 <implied 0 0 BPL > A=c0 X=ff Y= 2 PS=65 SP=ff Cyc=14617 PC=160f IR=88 <implied 0 0 DEY > A=c0 X=ff Y= 1 PS=65 SP=ff Cyc=14619 PC=1610 IR=10 <implied 0 0 BPL > A=c0 X=ff Y= 1 PS=65 SP=ff Cyc=14622 PC=160f IR=88 <implied 0 0 DEY > A=c0 X=ff Y= 0 PS=67 SP=ff Cyc=14624 PC=1610 IR=10 <implied 0 0 BPL > A=c0 X=ff Y= 0 PS=67 SP=ff Cyc=14627 PC=160f IR=88 <implied 0 0 DEY > A=c0 X=ff Y=ff PS=e5 SP=ff Cyc=14629 PC=1610 IR=10 <implied 0 0 BPL > A=c0 X=ff Y=ff PS=e5 SP=ff Cyc=14631 PC=1612 IR=85 <$nn 11 0 STA > A=c0 X=ff Y=ff PS=e5 SP=ff Cyc=14634 PC=1614 IR=a9 <#$nn 1615 0 LDA > A= 0 X=ff Y=ff PS=67 SP=ff Cyc=14636 PC=1616 IR=85 <$nn 1d 0 STA > A= 0 X=ff Y=ff PS=67 SP=ff Cyc=14639 PC=1618 IR=85 <$nn 1e 0 STA > A= 0 X=ff Y=ff PS=67 SP=ff Cyc=14642 PC=161a IR=a9 <#$nn 161b 30 LDA > A=30 X=ff Y=ff PS=65 SP=ff Cyc=14644 PC=161c IR=85 <$nn 20 0 STA > A=30 X=ff Y=ff PS=65 SP=ff Cyc=14647 PC=161e IR=a9 <#$nn 161f 50 LDA > A=50 X=ff Y=ff PS=65 SP=ff Cyc=14649 PC=1620 IR=85 <$nn 21 0 STA > A=50 X=ff Y=ff PS=65 SP=ff Cyc=14652 PC=1622 IR=a5 <$nn 95 80 LDA > A=80 X=ff Y=ff PS=e5 SP=ff Cyc=14655 PC=1624 IR=85 <$nn 91 90 STA > A=80 X=ff Y=ff PS=e5 SP=ff Cyc=14658 PC=1626 IR=a5 <$nn 96 78 LDA > A=78 X=ff Y=ff PS=65 SP=ff Cyc=14661 PC=1628 IR=85 <$nn 93 80 STA > A=78 X=ff Y=ff PS=65 SP=ff Cyc=14664 PC=162a IR=85 <$nn 2 0 STA > A=78 X=ff Y=ff PS=65 SP=ff Cyc=14736 PC=162c IR=85 <$nn 2a 0 STA > A=78 X=ff Y=ff PS=65 SP=ff Cyc=14739 PC=162e IR=a0 <#$nn 162f 7 LDY > A=78 X=ff Y= 7 PS=65 SP=ff Cyc=14741 PC=1630 IR=ae <$nnnn 1e37 cb LDX > A=78 X=cb Y= 7 PS=e5 SP=ff Cyc=14745 PC=1633 IR=ad <$nnnn 1e27 3a LDA > A=3a X=cb Y= 7 PS=65 SP=ff Cyc=14749 PC=1636 IR=85 <$nn 2 0 STA > A=3a X=cb Y= 7 PS=65 SP=ff Cyc=14812 The only things that looks strange to me is that the RESP0 occurs right after a write to WSYNC. The HMOVE occurs after a write to WSYNC as a good game should :-) And like I was saying HMP0 = $30 so it moves the player 3 pixels to the left at the STA HMOVE. Well I guess I better write some 2600 code to play with some of these interesting effects. Brad P.S. I'm not writing these traces by hand they're generated by Stella using a compile time option (they get very large after a few frames :-) -------------------------------------------------------------------------- Bradford W. Mott (bwmott@xxxxxxx) Computer Science Department http://www4.ncsu.edu/~bwmott/www North Carolina State University -------------------------------------------------------------------------- -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/stella.html
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