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Forums > C64 Productions > Limitations - Sprites in the Borders
2006-08-26 19:38
Wile Coyote
Account closed

Registered: Mar 2004
Posts: 646
Limitations - Sprites in the Borders

hello,

I was thinking, has anyone drawn up a doc with (pictures :)explaining *all known* possibilities with placing sprites into the border areas of the screen.

I know:
8 sprites can be placed in the upper and lower borders.
7 sprites can be placed in the side borders.

I was thinking, what about the corner borders,is that classed as a sideborder or a top or bottom border (8 sprites).

Another question :) when 7 sprites are placed into the sideborders can the 8th free sprite be placed into the main (center) screen areas or by opening up the side borders, is the option for an 8th sprite not available.

I am asking these questions as i am thinking about designs that use the border areas :)

thanks
/wec
 
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2006-08-27 17:48
tlr

Registered: Sep 2003
Posts: 1787
From mapping the c64:
Quote:
Bit 5: Bit 5 controls the VIC-II chip Reset line. Setting this bit
to 1 will completely stop the video chip from operating. On older
64s, the screen will go black. It should always be set to 0 to insure
normal operation of the chip.


Maybe it's only available on the very old VIC-II's (i.e 5 luma levels).
My original c64 was one of those. (i.e 9,8,7,1,7,8,9 looks like gold!)
It's in the attic right now though.
Roland has one of them...
2006-08-27 18:48
Graham
Account closed

Registered: Dec 2002
Posts: 990
The VIC-II's reset bit is a pretty mysterious thing. I have never encountered in real life, perhaps only the very early NTSC VIC-II's have it. I'm pretty certain that no PAL VIC-II has it, although you can never be sure...
2006-08-27 19:20
tlr

Registered: Sep 2003
Posts: 1787
But it is still a read/writeable bit?
Very odd indeed...
2006-08-27 19:45
tlr

Registered: Sep 2003
Posts: 1787
BTW, while poking around with $d016 I just noticed that the 38 column mode is borked in VICE (WinVICE 1.17 and 1.19 tested).
It covers 7 pixels to the left and 9 pixels to the right instead of 8, 8. :)
POKE53270,0
I reported it to the team just now.

EDIT: Or is it supposed to be this way? CCS64 is the same....
I have forgotten way too much stuff. :P

Note that the PAL C64 DTV covers 8/8... so I guess that one is wrong then?
2006-08-28 10:36
Jetboy

Registered: Jul 2006
Posts: 299
@_@
Just checked it on a real thing (its good to have real thing at work).
well... on standard c64 its 7-9 too.
so it seems there is no bug.
but all the time up to now i was sure it's 8-8 @_@

2006-08-28 10:36
Jetboy

Registered: Jul 2006
Posts: 299
Sorry for double posting.

At least now i finaly understand why opening sideborders works.
2006-08-29 06:43
Style

Registered: Jun 2004
Posts: 498
why was it so hard to understand? :)
2016-03-09 13:26
Smasher

Registered: Feb 2003
Posts: 519
oh yeah, 10 yrs later necro-posting! :)
so: sideborder sprites at badline, using no fld or similar tricks, no reu (hehe), etc... 4 is still the practical not theoretical max you can get, or?
2016-03-09 15:30
Flavioweb

Registered: Nov 2011
Posts: 463
If i understand things correctly, is possible to have 7 sprites (from 0 to 6) using INC $D016 at cycle 10 of the line (because of last 2 Write cycles of INC) to open border:
./victimer -b -s 127
  |                  1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 6 6 6 6 |
0 |1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 |
  |                   |===========01020304050607080910111213141516171819202122232425262728293031323334 353637383940===========|   |
--|----------------------------------------------------------------------------- -------------------------------------------------|
  |                 x x x W W W                                                                                 W W w            |
  |                    r r r r rcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgcgc g                 |
ss|3sss4sss5sss6sss7                                                                                                 0sss1sss2sss|
  |                  i                                                                                           i i             |
--|----------------------------------------------------------------------------- -------------------------------------------------|
  |                                ^(close sideborder)                                                           ^(open sideborder)
  |                           ^---FLI----------------->                                                      ^-----^(double line)  
  |                             ^---DMA Delay--------------------------------------------------------------^                       

 badline  sprenable=7f 
CPU:  3 (+ 5= 8) 
VIC: 54 (+ 1=55)
     63

x    - CPU regular cycles
W    - CPU write cycles
w    - CPU 3rd write cycle
c    - VIC video ram
g    - VIC color ram
0..7 - VIC sprite pointer fetches
s    - VIC sprite data accesses
i    - VIC idle accesses
2016-03-09 16:43
Joe

Registered: Apr 2002
Posts: 227
You can do quite a lot with the restrictions. Here are two examples from last year, coded by Firehawk/Hoaxers.

Disconnect, October
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