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2005-08-11 10:52

Shadow
Account closed

Registered: Apr 2002
Posts: 355

Let's talk about DYSPs!

Back when I started coding for the C64 (late eigthies) DYSPs where still cool, one of my alltime favorite parts is the 32-sprite multiplex DYSP from "The Larch 3/Bones".

Anyway, ofcourse I wanted to code my own, but since (atleast I think, my memory is a bit hazy on these things) depending on the number of sprites on a given rasterline you had a varying number of cycles available. This made it difficult to find out exactly how long to wait to be in the right spot for sideborder opening.

I couldn't quite figure it out, and instead my solution was to use 19 pixels high sprites, with blank lines on the first and last line, and then stretch them with $d017, so that I always had all sprites on every line, but adjusting the amount of "stretch" of the first and last line to get the sine movement.

All this was back in '90 or '91 when I was fourteen. Now that I'm older and (hopefully :)) somewhat smarter, I should be able to figure it out, but now I have forgotten all about the timings etc.

Exactly what is the "proper" way of doing DYSP timing?

2005-08-12 07:33

HCL

Registered: Feb 2003
Posts: 728

Answer 1: There is no proper way. Any way that works is ok.

Answer 2: The proper way is to let the computer to the job. Use some timer to tell how many cycles the sprites wasted, then you can't do any bad calculations yourself.

Answer 3: Do exactly like the rulers. Load the last part of "A load of old shit" by Horizon, and check it out. That's how to make a *proper* DYSP!

2005-08-12 14:08

Trash

Registered: Jan 2002
Posts: 122

I personally used the now so popular and cyclesaving trick jmp ($dc05). check the code in the buggy multiplexer contained in 'On tour' by Cult for a sample.

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