SPECTRA Advanced Graphics

[cheveron]

But in the initial posting I did not say anything about ULA+

Well you did mention it. If you hadn't I wouldn't have said anything.

And where I can find the documentation about the internas (memory map modes, etc.) of ULA+? The Spectra has excellent handbook that I do not want to miss again.

Well there's the tech spec:
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And Guesser wrote a guide to using the standard Spectrum mode from BASIC:
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The screen layout is exactly the same as for the standard Spectrum and Timex modes. The modes are selected the same way as on the Timex.
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Almost right, Most of us use DivIDE, but on the other side there are a lot of users demanding real tapes with new games, so I hope, Miguel can fix this problem in his spare time. Miguel does his job good.

I'm sure he will fix it, but since normal audio works fine (BEEP command right through to Shiru's beeper engines) I suspect it's one of those fiddly problems that will take a lot of testing with a scope to resolve.

You had should say it earlier that Timex 8x1 and Hires mode is available in the standard ZX Spectrum with ULA+ and not only in Timex and clones. You know, Retro-X supports Timex modes. Knowing the internals I can also add ULA+ modes, but in fact this does not stop me from supporting also the SPECTRA. I'm even sure, Games can support SPECTRA and ULA+ together with normal mode.

Well the Timex modes weren't always in scope for ULAplus, and most emulators (except SpecEmu) don't support them. But Miguel's hardware and Alessandro's FPGA cores do. Miguel has actually got a video of SPECTRA plugged into his issue 2 Spectrum while using the ULAplus board. Of course because SPECTRA uses video mirroring the ULAplus board is only functioning as a normal ULA in this setup.

The pitty part is that 128 has no YUV signals on the expansion bus. A fault introduced by Investonica. Otherwise it would be compatible apart from timing, but this could be easy added e.g. by a jumper to control Xilinx.

Well put that down to them going with RGB. The real pity about the 128 is that Sinclair didn't persuade Investronica to support the Timex video modes. Timex gave Sinclair all the tech details and it's really only a very minor change to the ULA design.

The Spectrum SE is a legend, but also a Spectrum +3S exists as a single prototype, and nobody supports it. And in the worst case I can thake the code of VBSpec and port it to PureBASIC (which is faster than VB), and add the SPECTRA modes myself. Unreal Spectrum Emulator is a very good candidate on the Sourceforge, but focusses on russian hardware. Anyway, a solution is not impossible.

Well if you're willing to do the work yourself that's another matter. Unreal Speccy drives me crazy because it only supports the Pentagon which means I can't run the standard ZXodus code on it. However it will be useful for testing the Pentagon version of the code when I get around to it.

Maybe it is a niche, but this would mean that ZXBC is a niche too, and I always supported niches that have potential. ULA+ has potential too and I will support it too, once I will have the real hardware.

Well all retro coding is pretty niche to be honest. But I think ZXBC has made retro coding a lot more accessible to people who don't want to learn machine code and find C a bit too intimidating. That's the reason I decided to use it for the game logic in ZXodus. I'm guessing that it will be possible to update the ULAplus boards once a fix is found for the audio issue. I know Miguel had a few PCBs made, although I don't know if they are all populated. If you're planning on supporting it then it may be possible to get one from him before it gets a public launch.

What if the game require all the Spectrum memory and overwrite the palette data with garbage?

Well that's the thing, the ULAplus ports were carefully chosen. To date I know of only two peripherals that they colide with (the MB02+ and the ZX Printer). Writing to the ULAplus will interfere with those devices (although a mod is possible for the ZX Printer), but writing to those devices will not interfere with ULAplus. So there's no danger of the palette being overwritten. The palette can be set before the game is loaded. Even if all the memory is used it should still be possible to change the values that are already in use for the attributes to use the full range of 64 colors.

Sounds excellent. Any idea how much it will cost?

As I'm not involved in the manufacturing I couldn't even guess. The cost of FPGAs and PCB manufacturing have come right down lately though. At a guess I'd say it would be no more expensive than a Spectranet, and probably quite a bit cheaper as it has fewer ICs.

Pauls converter is not perfect, but thic can be improved. Anyway, can you explain why larger palette make colours more distinguishable?

It's not just the larger palette, it's the red/green bias. The human eye is less good at distinguishing blue, so an evenly distributed palette with less variation like SPECTRA means some colors will look almost identical. Then there's just the fact that you can use palette cycling to get all 256 colours on screen with ULAplus which gives you a greater color range.

And I want to improve the number count of Spectrum software that is using SPECTRA. This does not mean that I will not support ULA+ in the future too. By the way, Jonathan Cauldwells Gams Designer supports ULA+ and it will support SPECTRA in the future aswell.

I know. But it's only in AGD4 where you get independent sprite color that you can really start to do interesting things with ULAplus like 24 color backdrops and palette cycling. I know I should do a demo to show it off but I'm short on time. Maybe when ZXodus is done I'll revisit it.

Thats right, it is hard to get the people support hardware. There is only one way to do this: Send free ULA+ chips to well known programmers .

Well I might consider buying boards for Jon and the Mojons as they've already created quite a few ULAplus titles. The thing is that a game that uses the full power of ULAplus isn't going to work on the original machine, so you either have to write two versions or limit yourself to providing an override palette, which is what they've done.

ZX Chrome has no ULA+ yet too. And I don't want to code only for emulators. Maybe I will purchase a russian clone with ULA+, but I prefer a drop-in replacement for the classic Spectrum.

There's ZX Badaloc Reloaded if you prefer to get one from Europe. The good thing about ULAplus is that it was always intended as a plug-in replacement. The bad thing is that it's only available in clones to date. The good thing is that I'm pretty sure it will eventually be available in its intended form. The bad thing is everyone may have given up on the Spectrum by then.

And I confess that ZXodus is a really great project. The problem is that it is compatible with a specific Spectrum model only, a model which I do not have yet.

Well it is targeted at a specific model because that's the one it will perform best on. But it will run on any 128K Spectrum compatible. It will even run on the Pentagon, but the attributes will be 8x8 instead of 8x1 and the color will be off. That's why eventually I plan on making a Pentagon version of the engine available. I already have a coder lined up to do the conversion.

Anyway, sorry to derail the thread. I'll shut up now and go back to the ZXodus thread.