My experiments with Atari 7800

[Eagle]

On 7/11/2023 at 5:02 PM, RevEng said:

Was that intentional?

I don't think so. But I'm not the author of this project.

He presents this on Lost Party last week in Poland.

All people there point to me as the first person to contact (I have no idea why 🤔 )

I must explain that in Poland Atari 7800 almost never exist.

Author of MariaEci sent me documentation and he will send me prototype soon.

So far I can say it's looks very very promising.

32MB ram, SD cart, RamCart, Maria rgb/s-video, TIA, extra playfield 1/2/4/8 bits, 8 Covox DMA.....

TIA mapped $D115-D11A

Maria $D120-$D13F

All registers mapped $D110-$D19C

 

I don't expect A8 people to jump in to Maria because it's very different than Antic.

But I would expect A7800 people to consider making games for MariaEci

 

[RevEng]

Ah, I see. Thanks for the clarification on your involvement. Very cool project regardless, and thanks for posting about it!

[Eagle]

Here is video from last year

MatGuru and his son other project Atari Next FPGA

 

Spoiler

sorry it's in Polish 

 

 

[Eagle]

BTW MariaEci could be a great opportunity for A8 programmers to learn Maria.

But FYI A7800 programmers can easily learn programming Atari Jaguar because Object Processor it's very very similar to Maria.

Below some my tests.

 

 

 

 

and some GPU test

 

 

 

 

 

[KrunchyTC]

On 7/15/2023 at 6:15 PM, Eagle said:

BTW MariaEci could be a great opportunity for A8 programmers to learn Maria.

But FYI A7800 programmers can easily learn programming Atari Jaguar because Object Processor it's very very similar to Maria.

Below some my tests.

 

 

 

 

and some GPU test

 

 

 

 

 

Those tests jag?

Edited July 22, 2023 by KrunchyTC

[Eagle]

Yes, but MariaEci can get similar results. 
 

Btw Maria ECI it’s now supporting SuperCart mapper, SN76489AN and much more…..

 

[KrunchyTC]

Nice!

[Eagle]

"Fixed" transparency for hires modes in MariaECI for Atari XL/XE

When bit 4 in DLL entry is ON then extended LineRam is used (two 160x5 bit - 1600 bits)

@SainT any chance to do similar "fix" for Maria in GD7800 in the future?

 

 

 

[SainT]

Maria ECI? What is this!? Does it support nicer high res video modes? I have been thinking about doing something similar, so this is very ingesting. I can certainly fix Maria bugs, too. I would enable this type of thing via another A78 header bit so as to maintain exact results between the actual console out and AV unless otherwise specified.

 

I have practically zero space free in the FPGA now, but I could offer different firmware versions. I could have one with just the single POKEY but extra Maria magic for instance.

[Eagle]

SN² cart is on his way, but MiSTer core for old SN cart is almost ready (base on @Kitrinx core but our version will be only for devs so far)

New SN cart for 7800 will support features from MariaECI and help develop on both platforms.

 

ps. sorry, no sound because my video grabber for some reason stopped recording audio 🤷‍♂️

 

 

 

[+karri]

11 hours ago, Eagle said:

SN² cart is on his way

What more could you possibly want? The current SN cart is already amazing.

[Eagle]

8 hours ago, karri said:

What more could you possibly want?

 

SN cart "only" use banking for $Axxx, $Cxxx,$Dxxx and $Exxx, new cart will do $8xxx,$9xxx,$Bxxx as well

8KB banking for RAM

FPGA player for VGM (just give him address in rom and will play)

Pointers - you can read any byte in rom without changing banks

Covox DMA

SN76489 stereo, Pokey, YM2612

and more

It's compatible with SN cart and you can send rom just using USB-UART cable

Also documentation will be publish so any one can make own cart.

I'm not gonna lie this is very demoscene oriented cart but in good hand will help make amazing games.

 

 

 

[+karri]

1 hour ago, Eagle said:

FPGA player for VGM (just give him address in rom and will play)

Ok. That is a pretty convincing feature. That would free plenty of time.

 

But I prefer the form factor of the original SN cart.

[Defender_2600]

On 7/28/2023 at 8:12 PM, Eagle said:

"Fixed" transparency for hires modes in MariaECI for Atari XL/XE

When bit 4 in DLL entry is ON then extended LineRam is used (two 160x5 bit - 1600 bits)

@SainT any chance to do similar "fix" for Maria in GD7800 in the future?

 

 

 

 

Amazing work! Will enabling this feature be an option? I ask this because in some circumstances the background color could be used voluntarily as an additional color and the transparency would create some defects to the graphics when the sprites overlap other sprites or tiles.

 

And just out of curiosity, would any other magic be possible for Maria? For example I'm thinking about the placement limits of C1 in 320B mode.

 

[Eagle]

Bit 4 in DLL entry will enable Extended Hires mode for MariaECI, also DLL entry will take 7 bytes give some extra features like for example 32 bit address for Maria gfx bank

SN² cart will not support this but 7800GD could easily and it's up to @SainT. When we finish testing SN² cart and MariaECI I will share all details.

14 minutes ago, Defender_2600 said:

And just out of curiosity, would any other magic be possible for Maria? For example I'm thinking about the placement limits of C1 in 320B mode.

Yes.

 

2 hours ago, karri said:

But I prefer the form factor of the original SN cart.

Me too. But this is for YM2612.

For example we have YM2151 for few years for now and no one is using.

I did few demos, Paul and Mike did some players but Midi style.

Playing YM2151 vgm it can take up to 500 bytes per frame with 32 cycles delay between writes.

No chance to get very good music in game. All arcades and other machines with YM2151 have extra CPU Z80 for just playing the music!

I don't want Z80  so we will use FPGA to play VGM but you don't have to use it.

Instead of YM2151 we should use YM2413, but someone decide long time ago to put YM2151 in XM module 🤷‍♂️

I was planning to put YM2413 on SN cart and even I sent few chips to Rafal (BTW  TailChao was planning use YM2413 for Rikki but he was afraid of fake chips)

But we have now SN² cart  

 

[Defender_2600]

11 minutes ago, Eagle said:

Yes

 

WOW!

 

So, the next question may seem like asking too much but maybe it would also be possible to have two different colors in the same pair of pixels with 320C mode?

 

[Eagle]

1 hour ago, Defender_2600 said:

So, the next question may seem like asking too much but maybe it would also be possible to have two different colors in the same pair of pixels with 320C mode?

Transparency "fix" is base on how Maria is writing to LineRAM (we doubled LineRAM)

 

You are asking for changing reading.

In 320B mode you already have 2 bits per pixel in gfx data, just Maria can't write this to LineRam.

320C is different and possible for MariaECi but only because Maria it's done from scratch in FPGA and have no limitations like normal Maria.

MariaECI can read up to 500 bytes per line (normal Maria about 130 max)

For 320C fix you will have to double amount of data.

With transparency "fix" you can put 2 sprites 320C on top of each other.

 

ps. Just came to me that with doubled LineRAM we probably could try mix 160 and 320 modes 🤔 🤯

In 5 bytes header we could use one spare bit to change CTRL read mode on the fly 

I need ask smarter people than me if this is possible  

 

edit:

hmmm we could use bit 0 for mix mode

but also use bit 1 for 320px sprite movement  

 

Edited August 11, 2023 by Eagle

[Defender_2600]

Awesome stuff!

 

[Eagle]

We can mix 160 and 320 modes 🥳

[Defender_2600]

  

[Eagle]

It’s alive 😂

 

[Eagle]

And it's running SN cart demo.

Testing and adding all new features will take some time but will be lot of fun  

 

 

 

[Defender_2600]

On 8/11/2023 at 9:13 PM, Eagle said:

MariaECI can read up to 500 bytes per line (normal Maria about 130 max)

For 320C fix you will have to double amount of data.

With transparency "fix" you can put 2 sprites 320C on top of each other.

 

ps. Just came to me that with doubled LineRAM we probably could try mix 160 and 320 modes 🤔 🤯

In 5 bytes header we could use one spare bit to change CTRL read mode on the fly 

I need ask smarter people than me if this is possible  

 

edit:

hmmm we could use bit 0 for mix mode

but also use bit 1 for 320px sprite movement  

 

Some questions:

 

- Would it be possible to have an additional palette for the 320C mode, so 3 palettes instead of the current 2?

 

- Can 320C mode be used with both 160A and 160B? And will the colors of the palettes have to be shared between the two modes?

 

- Assuming 320C + 160A will all 8 160A palettes and both 320C palettes be available?

 

- We can overlap 320C + 320C on top of 160A, so we get more colors?

 

Thanks for the replies.

 

[Eagle]

Hi @Defender_2600

I just spoke with Mat and he will increase LineRam so we can have 8 pallet in 320 modes.

For 320C I would like to have P0C1 P1C1 P2C1 P2C1 and P0C3 P1C3 P2C3 P3C3 and....

I'm thinking about 320D but nothing coming to mind.

I hope you will like it  

MariaEci FPGA has 25K LUT's and Maria core was written from scratch and it's taking about 30% MiSTer Maria LUT's.

I hope that will be possible to increase 7800GD LineRAM and fit in FPGA

Would be nice to have new modes not only for MariaECi and MiSTer but also for 7800GD

 

 

[SainT]

I have virtually zero FPGA space left on the 7800GD, so I won’t be able to do anything remotely complex unfortunately! 
 

Are you driving HALT from your cart for your new Maria? Or are you just using RAM on the cart for the new Maria functionality?

 

The only thing I thought might be useful (and easy) is changing the DMA for 160x4 such that it can write 16 colours by remapping the incoming bytes to skip the zero entries at 4, 8, 12.