Creating graphics on TT with VGA card

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mgi
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Creating graphics on TT with VGA card

Post by mgi »

How can I create demo/graphics in 1024x768 in 256 colours for example on TT?

I can play in assembler with 4 bit planes in low ST resolution and 16 colours to create a game but how could I use the possibilities the Nova and Mach64 offers?

Cheers
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stephen_usher
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Re: Creating graphics on TT with VGA card

Post by stephen_usher »

You’d have to target a specific card, learn the way that the underlying VGA chipset works and hit the hardware or purely use slow VDI interfaces.
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mrbombermillzy
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Re: Creating graphics on TT with VGA card

Post by mrbombermillzy »

mgi wrote: Sun Jul 04, 2021 6:57 am How can I create demo/graphics in 1024x768 in 256 colours for example on TT?
Ok, you can do this the easy (slower performing) way:

Install the relevant working driver for your specific graphics card and then write to the TT screen address. This then gets shadowed to the ISA cards screen display by the driver.

The faster way:

Grab the specific document for your ISA card (Mach64/ET4000/whatever). Learn the registers and memory mapped layout that the card uses. Then write to these addresses directly using VME address area in TT RAM. Its still not going to be mega fast, but maybe you can improve on the other option.

I have some sporadic documents for some ISA cards if you want to have a look at how simple it all is :lol:
mgi
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Re: Creating graphics on TT with VGA card

Post by mgi »

Sure, happy to have a look, any help appreciated!
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mrbombermillzy
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Re: Creating graphics on TT with VGA card

Post by mrbombermillzy »

OK. I dont have much info for the Mach64 specifically (which is what you seem to have). However, the documents in here should be at least downwards compatible with that card (they are Mach32 and earlier documents). Also theres some info about programming for the Nova card.

I have some other documents which are related, but I wont include them as they are related to whatever RAMDAC was on your card.

ATI Legacy docs.zip
(22.8 MiB) Downloaded 111 times

If you want to have some quick 'fun':

Install the drivers for your card (best bet is to try the latest ones from Idek's site): https://www.atari-forum.com/viewtopic.p ... &start=100 and ensure they are working correctly (i.e. you boot successfully to a high res/colour desktop on your external card output.)

Now create an ASM (or C if you prefer) program that writes to the TT graphics RAM. You will see the output mirrored onto the VME card output. Bear in mind, the Mach card may be in packed pixel format rather than CLUT, so you'll have to adjust your screen writing/write amount depending on the bitdepth and screen dimensions used.

I would have posted an example, but the TT HDD has been removed and will be a pain to replace ATM.

Anyhow, hope this helps.
mgi
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Re: Creating graphics on TT with VGA card

Post by mgi »

Big thanks! I know what I will be doing over the next few late nights :D
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mrbombermillzy
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Re: Creating graphics on TT with VGA card

Post by mrbombermillzy »

No problem. Please keep me updated on your progress. :)
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