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Author Topic: External colour input (Read 5924 times)

Online gflorez

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External colour input
« on: 2016.December.02. 12:51:27 »
TVC ugyanaz EXTCOL \ és EC0, EC1, EC2, EC3 jeleket.

Milyen interface ez?

Volt gyakori, hogy a korszak?

Tud elérjék a Sprite prototípus?


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TVC has the same EXTCOL\ and EC0, EC1, EC2, EC3 signals.

What kind of interface is it?

Was it common on that era?

Can you reach the Sprites Prototype to study it?

Offline Zozosoft

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Re:External colour input
« Reply #1 on: 2016.December.02. 13:10:34 »
TVC ugyanaz EXTCOL \ és EC0, EC1, EC2, EC3 jeleket.

Milyen interface ez?
Külső színbemenet, ugyanúgy mint az EP-n

Quote
Volt gyakori, hogy a korszak?
Nem hinném. De az EP-t és a TVC-t ugyanaz a csapat tervezte.

Quote
Tud elérjék a Sprite prototípus?
Csak a neten lévő képeket ismerem :-(


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Quote
TVC has the same EXTCOL\ and EC0, EC1, EC2, EC3 signals.

What kind of interface is it?
External color input, same as on EP.

Quote
Was it common on that era?
I don't think it. But same team developed the EP and TVC.

Quote
Can you reach the Sprites Prototype to study it?
I only know the photos on the net about it :-(

Offline pear

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Re:External colour input
« Reply #2 on: 2016.December.03. 17:05:01 »
Dokumentáció az van bőven :-)
Are there available any schematics ? I read that this computer has been built entirely without the use of specialized chips. I could try to clone it.
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Vannak-e rendelkezésre olyan rajzok? Azt olvastam, hogy ez a számítógép épült teljesen használata nélkül speciális chipek. Megpróbálhatnám klónozza azt.

Offline lgb

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Re:External colour input
« Reply #3 on: 2016.December.03. 17:48:45 »
Are there available any schematics ? I read that this computer has been built entirely without the use of specialized chips. I could try to clone it.
---------------------------
Vannak-e rendelkezésre olyan rajzok? Azt olvastam, hogy ez a számítógép épült teljesen használata nélkül speciális chipek. Megpróbálhatnám klónozza azt.

Well, it's Hungarian book, but there are many hw related info and some "bit abstracted" schematics too (with description how it works, but in Hungarian ...):  http://tvc.homeserver.hu/doc/konyvek/tvchardver.pdf However this is not exactly a precise schematics you would expect, I think! I'm not sure if there is a detailed, full-featured schematics on the computer ...

Btw, if you want to clone, there is another - even more simple - Hungarian computer, the "Primo" (and it's b&w, the advanced colour model was not even released later but planned, if I know well) which does not even use "complex" chips (other than the Z80/U880, U880 is a hmm an "eastern block" clone of Z80 hehe ...), unlike the TVC here which contains a specialized chip at least (though a common one!) the 6845 CRTC. Though it was already done it seems: http://primo.homeserver.hu/html/epitesutanepites.html

Offline pear

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Re:External colour input
« Reply #4 on: 2016.December.03. 18:32:12 »
I ask about TVC64 not coincidentally. It is most similar to the Enterprise.
Maybe it would be easier for me to recognize how works the inputs EXTC and EC0-EC3. I'm afraid a little of doing experiments on expensive original EP.
The 6845 CRTC chip is quite easily accessible. It was widely used in many computers (Amstrad/Schneider CPC, early PC graphic cards MDA and CGA).

Offline lgb

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Re:External colour input
« Reply #5 on: 2016.December.03. 18:59:54 »
I ask about TVC64 not coincidentally. It is most similar to the Enterprise.
Maybe it would be easier for me to recognize how works the inputs EXTC and EC0-EC3. I'm afraid a little of doing experiments on expensive original EP.
The 6845 CRTC chip is quite easily accessible. It was widely used in many computers (Amstrad/Schneider CPC, early PC graphic cards MDA and CGA).

Yeah, I see, I just mentioned Primo, since it's an interesting stuff, that there is no special IC (AFAIK!) in it, other than Z80, not even something like the CRTC, or custom stuff, like the ULA in Speccy, or Dave/Nick in EP, etc. But surely, I see your point. I think, you can't damage an EP with those inputs too much ... AFAIK, EC0-EC3 and EXTC both of all are inputs, normal logical evel, etc, so you can even build some buffer between them, etc.

In theory, EC0-EC3 are colour inputs which are treated if EXTC is driven active (low active, if I remember correctly). Also, some Nick I/O ports, you can tell how they are should be used. Since I *still* (please do not comment, hehe) don't have a usable EP for real, I can't try, but I already suggested, that somebody should try to drive EXTC active externally and only put a constant "colour" onto EC0-3 (eg, ground all of them, maybe on some resistor though, just to be safe). Then on 0x80 port of Nick, the handling of external colour input should be "set up" for as you like, and you can try, what happens on the screen when you drive EXTC active or inactive, or even setting EC0-EC3. My idea, that it should display that colour. Since it's more or less a constant value on EC0-3, and not sync'ed to the pixel clock, etc, surely it looks all on the screen or so, but it's a good and quite simple start to see, if it works this way at all. That's what I think you should not cause any damage, since they are inputs etc, but hey, I can't be sure for sure :) sure-sure :D

Offline lgb

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Re:External colour input
« Reply #6 on: 2016.December.03. 19:10:22 »
There are some interesting questions though, eg how external colour values are interpreted in different Nick colour mode LPBs, and for example can you "command" the max resolution even in the case when you have 256 colour mode, so Nick can produce only "blocky" graphics at all. Another interesting fact, that with external colour, - at least according to my idea ... - some can implement an "extra high 16 colour mode" using external hardware providing the pixel data. Then you can even "mix it" with internal Nick graphics in some way. So not only for sprites it can be interesting - maybe there can be SymbOS higher resolution mode this way :) ... though the problem that the 'video ram' is external than to the additional hardware ...
« Last Edit: 2016.December.03. 19:17:42 by lgb »

Online gflorez

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Re:External colour input
« Reply #7 on: 2016.December.03. 19:50:13 »
Or totally the contrary, a smoth scrolling background and using Nick-Z80 to move the sprites...
« Last Edit: 2016.December.03. 19:55:52 by gflorez »

Offline pear

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Re:External colour input
« Reply #8 on: 2016.December.03. 19:57:43 »
At now, I only research the subject, but curiosity consumed me :idea: 

Offline lgb

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Re:External colour input
« Reply #9 on: 2016.December.03. 20:26:43 »
:) I guess, somebody with the needed site admin rights should move the conversation of external colour into its place, somewhere in the :UK section :-D

Offline Zozosoft

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Re:External colour input
« Reply #10 on: 2016.December.03. 22:01:49 »

Offline Zozosoft

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Re: External colour input
« Reply #11 on: 2016.December.03. 22:05:37 »
TVC Spectrum emulator generate the Spectrum screen to the external color input.
Using this method also will be good idea for new Enterprise Spectrum emulator, because no attributom conversion needed.

Offline lgb

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Re: External colour input
« Reply #12 on: 2016.December.03. 22:52:15 »
TVC Spectrum emulator generate the Spectrum screen to the external color input.
Using this method also will be good idea for new Enterprise Spectrum emulator, because no attributom conversion needed.

Wow! I haven't known if there was _any_ usage of the external colour input feature. Nice :)

Offline Zozosoft

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Re: External colour input
« Reply #13 on: 2016.December.03. 23:01:32 »
On Enterprise, I suggest this as first try: put a 4 bit counter to the Nick clock, these 4 bit connected to the EC0-EC3, and lets see what happening when EXTC active.

What I wait: external color input will select one of the 16 colors, instead the current pixel colour (priority can be selected, see the Nick documentation). And I'm 99% sure 16 colors can be used with Hires 2 resolution. See the Text 80, it is use 8 colors in this mode.

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Re: External colour input
« Reply #14 on: 2016.December.03. 23:23:03 »
Exciting :) Using the "dot clock" basically will create some kind of "chessboard" or "vertical stripes" like stuff if I am correct exactly at hires pixel "wide". What would be interesting to set up an LPT with more LPBs with different colour + video modes, and watching what happens, is there any effect Nick take account in relation of the external input based in its internal mode. it's interesting though what would happen with like 256 colour LPIXEL mode, which is kinda blocky with Nick, can external colour only override a "Nick pixel" always, or the atomic smallest possible pixel even in this case. And surely also the question what the 4 bit external colour is interpreted as if the mode is palette based or not (ie: 256 colour mode, where there is no palette ... though the external colour may use the LPB palette + BIAS even in this case?).