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Shadow
Account closed
Registered: Apr 2002
Posts: 355 |
Is 120 the max number of full height sprites that can be displayed?
I've been on a nostalgia trip and checking out some demos from the real oldschool, record-breaking times. So I started thinking a bit about the world record for most sprites in a multiplexer. I started calculating, and got the following:
8 sprites can be displayed per 21 lines (since a sprite is 21 pixels high). Now you have 256 y-positions available to place sprites on. That should give us 96 or maybe 104 (I wasn't quite sure on this).
Since I saw demos with 112 and even 120 sprites (think it was in Ice Cream Castle/Crest), this couldn't be the limit.
Anyway, I started coding on a little test program and discovered that sprites placed on position $01 to $1e was displayed twice (both in the upper and lower border. I guess this is common knowledge, but I've been out of the loop for a while!)
Now, those $1e lines gives us the possibility to display two batches of 8 sprites that essentially gets doubled, thus we have 104+116 = 120 sprites as the absolute maximum.
Is this correct reasoning? Any oldtimer hardware specialits who can shed some light on this? |
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CyberBrain
Administrator
Posts: 392 |
I thought multiplexors was >8 sprites that all moves past eachother in y.
Maybe a little bad explained, but like you can make a simple sprite routine that moves 8 sprites up/down in a sinus movement, an example of what i thought was a multiplexor is >8 sprites moving up/down in a sinus movement.
(...and moving them in x makes it look sweet :) )
Are you sure multiplexors are just displaying the same sprite more than once in a frame?
(would be nice with a library of all these words on the net) |
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JCB
Account closed
Registered: Jun 2002
Posts: 241 |
Sorry, brain lost focus in my last post, I meant "moving more than 8 sprites (sorting) in an intelligent manner". Having just read my last post again it's utter rambling nonsense :) I'd just woken up, thats my excuse. Still not properly awake so this post won't make sense either haw |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
JCB wrote:
"hmm to me a multiplexer has to be usable for moving the sprite more than once per frame in an "intelligent" manner. Still, thats just my opinion ;)"
i dont think that it has anything to do with opinions. "multiplexing" is a term which has a certain meaning of using something multiple times. for example, some older processor multiplex their adress lines to allow 16 or 24 bit adresses over an 8 bit adress bus. now adapting this term for sprites would simply mean that you use a single sprite multiple times. multiplexing does not implicate any kind of "intelligence", in fact all the hardware multiplexing is done without intelligence at all. just very basic logic.
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JCB
Account closed
Registered: Jun 2002
Posts: 241 |
I know where the word multiplexing comes from and it in fact originally has nothing to do with computers ;) And I still believe that I am right to have an opinion on its use in the realms of c64 sprites. Someone gave the use of more than 8 sprites displayed using a SORTING method the term multiplexing, the fact that others then decided to encompass just more than 8 sprites on screen doesn't make it correct. |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
honestly, this is the first time ever i hear that multiplexers should include sorting routines. no coder i ever met used that term in that way, and thinking about it's meaning on other subjects it wouldn't make sense to implicate sorting.
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cadaver
Registered: Feb 2002
Posts: 1153 |
Ah.. I could imagine JCB & MT having a quarrel about Turrican boss-display routine:
JCB: That routine isn't a multiplexer, 'cos it isn't sorting anything
MT: It doesn't *need* to sort, the order is fixed
JCB: So, you even admit it yourself, it isn't a multiplexer
MT: WTF??
:) |
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Dr. Jay
Account closed
Registered: Jan 2003
Posts: 32 |
Silly argument.
It's simple, really. Multi - latin root, i.e. "many".
Plex - from latin plico - fold or wrap, i.e. comPLICated literally means "many things together".
Multiplex - basically folding or wrapping the display so the sprites appear multiple times.
Beyond that is really opinion.
JCB, you like sorted sprites? Fine. But blue is blue and multiplexed is multiplexed. If you're worried about something being sorted, then worry about multiplexed sprites with a sort routine. There is NO implication of "sort" in the word multiplex, anywhere. Now whenever you hold your own demo competition, you are certainly free to say that any multiplexed submissions must have proof of an intelligent sort.
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CyberBrain
Administrator
Posts: 392 |
Erhm... i don't know what's right or wrong... But the question is not the origin of the word, or in which historical context it can be placed. It's about how it's used in the C64 Scene.
I know that the only places i've seen the use of the word "multiplexer", is in demos with those sort routines (where >8 sprites moves around between eachother). That's why i got pretty puzzeled by grahams definition.
Not that i say Graham is wrong (coz' i'm not at all sure) but i've just never seen "multiplexer" used for anything else than the sorting-thing. |
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JCB
Account closed
Registered: Jun 2002
Posts: 241 |
Well it IS a silly argument and I was just trying to point out that IN MY OPINION it isn't a multiplexer, the fact that when I started coding c64 more than 8 sprites was just known as a sprite split and one that would allow you to move the Y positions and sort them was known as a multiplexer. Go back, check your scene history, try to find me a demo that claims to use a multiplexer when the 1st games/demos started using them and it WILL sort the sprites, nobody USED to claim having more than 8 sprites on screen was anything of the sort. I'm sorry if you guys these days have to insist on using this word when it never used to be so all encompasing, I'm just sticking to what I SEE as being a multiplexor.
Cadaver, I don't care if MT would think its a multiplexor, he didn't invent it, so if he wants to call it that then fine, I'll say it one more time IN MY OPINION it isnt, you can do all the RECORD multiplexer demos you want and sit waiting for $d012 to equal something then move your sprites Y pos but it won't change my mind.
Dr. Jay, same goes for you blue is blue, wow cool argument. I'm not trying to piss people off for the sake of it but I've always know the word to mean one thing, I also (Graham) know lots of coders who would disagree with you and agree with me.
ps one LAST time IN MY OPINION. you guys ganging up on my won't change my mind ;) you're not the be all and end all of c64 coding, you didn't invent any of this I'm just pissed that I seem to be unable to have an opinion on something and being told by people what multiplexer means in latin so that makes them right. wtf ?!?
You have your opinion, I'll have mine. ok?
Get the message now, IN MY OPINION ;) |
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CyberBrain
Administrator
Posts: 392 |
Yeah... I think that, in the old days, if you claimed you had done a 32 sprite multiplexer, and it turned out that all you did was showing 32 sprites on the screen at once, people would consider you pretty lame.. :) Have anyone got an example of a demo where the word multiplexer isn't used for the sorting thing? |
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