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Ninja
Registered: Jan 2002
Posts: 406 |
Release id #90651 : REU-Colors
Skate: Check this page from AAY. You can use a fixed C64-address for transfers. So this prog dumps generated REU-content into $d020, 1 byte per cycle (something like 'hello world' in my book). This mode was really useful for anaylizing the SID-waveforms, when $d41b or $d41c could be dumped into the REU every cycle.
Have a glimpse at the register descriptions in AAY and you have a good idea what the REU is about. For details, read Womo's excellent manual.
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Sander
Registered: Jan 2002
Posts: 487 |
From Pouet:
Quote:@xeron. You can give the REU a memorylocation where to write his own content into. This could be used to copy memoryranges from or to the REU. As the REU uses DMA it can copy 1 byte per cycle. Futhermore you can copy a memoryrange from the REU into *one* address on the c64, only (or vice versa). That means you can write f.e. 4000 bytes of data into $d020 (BackgroundColor) in 4000 cycles. So you can alter the color ca. 4-6 times faster as the CPU could (inc $d020 needs 6 cycles, STA needs 4). My effect alters the backgroundcolor each 8 pixels in x (rasterbeam goes 8px/cycle).
More Infos can be found in the source, included in the package. 8) |
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Trash
Registered: Jan 2002
Posts: 122 |
What all of this mean is that you for instance could create a brand new FLI-mode, where you would get 4x2 pixel with three freely selectable colors plus $d021 (trigger badline every second line, stream new d800-data and change d018). You can also make fullscreen allborder unexpanded graphics using Xfff as the target of your datastream. Furthermore you possibly (haven't tried this one yet but i've gave my other suggestions a shot) could make the sideborder go away with more than 4 sprites on a badline. Plots and other sets of code depending on filling an area quickly can gain from the REU, you could stream very complicated animations in realtime (just like Crest does), playing samples with a higher samplerate...
The possibilities with a REU are many and then keep in mind that I have a limited set of fantasy.... |
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Mace
Registered: May 2002
Posts: 1799 |
I see a new world of demos opening right in front of us.
But someone else already said that this would reduce the C64 to a mere graphics card...
Is it bad, or...? |
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enthusi
Registered: May 2004
Posts: 675 |
it is what killed i.e. the Atari Scene.
The c64 scene got this steady due to limiting itself to stock c64 IMHO.
Though I do like stuff at the expansion port, (NEOram, EasyFlash, RRnet), I dislike (does anyone care?) the REU for its DMA capabilities. It is more like a new CPU or System.
Reu (with DMA) can do what _in principle_ could not be done without.
Fun to experiment with (which has been done in the past numerous times), fun to exploit (BluReu, which in fact rather uses 1541u capabilities than 'REU') but not fun as a platform (since there is the DTV already for example).
My 3 cents. |
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chatGPZ
Registered: Dec 2001
Posts: 11123 |
i agree with enthusi there :) |
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Ninja
Registered: Jan 2002
Posts: 406 |
Trash: Just start coding before your fantasy goes too wild ;) You have to setup a bunch of registers before doing DMA. This might limit the REU-usage for rasterline-based effects.
Also, I agree, there is a reason that it wasn't heavily used for demos so far. BluREU was fun, but there won't come a trend out of it... |
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Mace
Registered: May 2002
Posts: 1799 |
We'll see about that REU. |
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Trash
Registered: Jan 2002
Posts: 122 |
@Ninja: I have experimented with the REU and the allborder fullscreen graphics are doable (with some limitatons), the fli-mode is doable and doing tech tech in the lower border is doable (with some limitations). Setting up the REU can in most cases be done prior to streaming the data, in some cases it will need some fixing during the rasteroperations.
I wont go wild, most likely i wont release anything either, I did all of this a couple of years ago and presented some stuff @ LCP 2004, I'm only saying that theese effects can be done (except for the more than four sprites on a scanline which I havnt tested but it sure is possible I think) using a REU and possibly someone else will find other and cooler effects. |
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Wisdom
Registered: Dec 2001
Posts: 90 |
Forget about "the era of REU demos" and similar fantasies. It will not happen. And it will not happen for a good reason: C64 coding is all about coding for stock C64.
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taper
Registered: Dec 2001
Posts: 119 |
I too agree with Enthusi. I loved BluReu and it was a worthy winner in the BP wildcompo, and it's fun to see people experiment and do stuff with add-ons. But, the reason why the c64 scene is much more healthy (in my eyes) than for instance the amiga scene has probably a lot to do with the fact that it's more fun to push the boundries of a fixed architecture. The amiga turbocard race was not healthy for the amigascene, it divided it in even smaller segments. And let's not even start with the PPC cards, turning the amiga into a whole different architecture.
That said, I hope I'm forgiven for running Antidote on a Super CPU... Atleast it's in no way a must for running a telnet:able C*Base BBS, just makes it faster. :)
...sorry for hi-jacking the thread... |
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Skate
Registered: Jul 2003
Posts: 491 |
Thanks Ninja. These information are pretty helpful. |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
Should be mentioned: Snata. Did the same kind of REU $D020 streaming 7 years ago :) |
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chatGPZ
Registered: Dec 2001
Posts: 11123 |
that reu talk reminds me again.... WHERE is that reu demo from masters design group? (is it one of those which are here already?) |
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Frantic
Registered: Mar 2003
Posts: 1627 |
You can also use a REU to play 4bit digis at 985247hz, which is... too much. :)
//FTC |
