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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: 580
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 19:45
tlr

Registered: Sep 2003
Posts: 1246
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
Account closed

Registered: Jul 2006
Posts: 179
@_@
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
Account closed

Registered: Jul 2006
Posts: 179
Sorry for double posting.

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

Registered: Jun 2004
Posts: 487
why was it so hard to understand? :)
2016-03-09 13:26
ZeSmasher

Registered: Feb 2003
Posts: 367
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: 387
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: 168
You can do quite a lot with the restrictions. Here are two examples from last year, coded by Firehawk/Hoaxers.

Disconnect, October
2016-03-09 20:23
soci

Registered: Sep 2003
Posts: 438
If i understand things correctly, is possible to have 7 sprites (from 0 to 6)

I assume PAL VIC-II here.

It's not sprites 0 to 6 but 1 to 7 and can be done with a SCPU for example. (Popel Premiere)

Once I've tried to write between the end of character DMA and sprite 0 DMA (using custom hardware) but it's futile. AEC is low in that "gap" so the write ends up in RAM and not in the VIC-II.

So it seems the maximum is 7 sprites on a bad line if you want to open the border with a PAL VIC-II.

No I haven't tried to route around the PLA to see if the VIC-II accepts the write or not. Went too far already ;)

However with a NTSC VIC-II it might work as there's a wider gap and even BA opens for a cycle.

Did anyone tried 8 sprites with open border and badlines on NTSC using a SCPU? In VICE it seems doable, but it does not mean it really can be done.

It could be a world-first! ;)
2019-06-25 20:12
Oswald

Registered: Apr 2002
Posts: 4484
8 sprites without badlines is not possible? sprite 0 conflicts with the d016 write needed ?
2019-06-25 20:27
Compyx

Registered: Jan 2005
Posts: 470
Nah. 8 sprites is very well possible without badlines. Just use any RMW instruction to avoid the sprite 0 DMA,ie DEC $D016: INC $D016.
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