Author Topic: Mega SG and FPGA Jailbreaking  (Read 4137 times)

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Offline Galron

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Mega SG and FPGA Jailbreaking
« on: May 18, 2019, 05:51 AM »
What is a jailbroken Mega SG potentially capable of? I mean right now it can do SC-1000, Master System, Genesis, and even Coleco Vision.... and we also know the system has standard Atari plugs, just like old sega systems used.... Is it possible for FPGA to also be reprogramed to handle Atari games and use Atari controllers, if someone included the cores with jailbreak mod?


Could Sega-CD games also be made to run off SD card without having to need the external CD hardware with a proper core? Or perhaps some kind of external SD/USB based digital thing that could be attached to the side port of the Mega SG to 'simulate' a CD drive, but actually be device similar to PSIO for Playstation?

Offline EmperorOfTigers

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Re: Mega SG and FPGA Jailbreaking
« Reply #1 on: May 18, 2019, 11:57 AM »
I'm absolutely no expert but I would say Atari would be very possible considering most Atari systems are weaker than the Genesis. It would just require Kevtris to implement it.

As for Sega CD. I'm not really sure as I would imagine the hardware to replicate it would be decently big so running the games and replicating the Sega CD unit might be too much. I would imagine it's very possible if a separate unit was made to do it. Again to be fair it would probably be up to Kevtris to implement it if it's possible.

So overall without being an expert at all I would say it's probably possible somehow. It's just if Kevtris wants to/or is allowed to implement it somehow.

Sorry for the vague answer but I saw nobody replied so thought I would try and answer the best I can.

Offline Galron

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Re: Mega SG and FPGA Jailbreaking
« Reply #2 on: May 18, 2019, 06:50 PM »
Well the thing is its all a matter of what FPGA they are using too, and how much space is possible. There is apparently some work being done to add Sega CD to MISTer for example...

This if I'm reading it correctly... (if it s not some kind of physical 'add-on' thing for the MISTer with an additional FPGA)

https://twitter.com/AshEvans81/status/992085258098106368


Looks like PSI0 might look into a Mega CD option alternative similar to the PSI0 and their DCI0 as well.... Which hopefully might be compatible with the Mega SG?

https://www.cybdyn-systems.com.au/forum/viewtopic.php?p=12051#p12051


Quote
t's just if Kevtris wants to/or is allowed to implement it somehow.

Wasn't it Smokemonster who did the jailbreaking, and added the current core compatibilities? He used to post here, but I don't know if he does anymore. He would be the person I'd love to ask, if he could include more cores in his jailbreak... At least Atari stuff....

As I understand it who ever made the jailbreak for the original Analogue NT or smaller one, actually included many different cores from Atari up to SNES/SEGA?
« Last Edit: May 18, 2019, 06:54 PM by Galron »

Offline Relikk

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Re: Mega SG and FPGA Jailbreaking
« Reply #3 on: May 18, 2019, 11:35 PM »
Wasn't it Smokemonster who did the jailbreaking, and added the current core compatibilities?

No. He just releases them to the public. It's all Kevtris' work.

Offline Galron

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Re: Mega SG and FPGA Jailbreaking
« Reply #4 on: May 19, 2019, 12:49 AM »
I wish we could ask Kevtris about it..... I have old Atari controlers and I've love to see if they worked!

Offline EmperorOfTigers

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Re: Mega SG and FPGA Jailbreaking
« Reply #5 on: May 19, 2019, 02:11 PM »
I wish we could ask Kevtris about it..... I have old Atari controlers and I've love to see if they worked!
Kevtris has been asked about things before but never answers questions about Jailbroken firmware. I don't know if he is actually allowed to discuss it. It could be part of his contract with Analogue.

Offline Galron

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Re: Mega SG and FPGA Jailbreaking
« Reply #6 on: May 19, 2019, 07:41 PM »
Well obviously they aren't going to put SNES core on the Sega MG, or the Sega cores on the SNES... Since that would be hurt the sales of both products.

Offline Davestra

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Re: Mega SG and FPGA Jailbreaking
« Reply #7 on: January 20, 2020, 08:08 PM »
Hmm, that makes sense, Galron. It's always about the sales figure, I guess.

Offline goldenband

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Re: Mega SG and FPGA Jailbreaking
« Reply #8 on: February 29, 2020, 04:46 AM »
I'm absolutely no expert but I would say Atari would be very possible considering most Atari systems are weaker than the Genesis. It would just require Kevtris to implement it.

For the record, emulating the Atari 2600 well is actually quite CPU-intensive. It's a finicky system that requires exact timing and emulation of really bizarre hardware quirks for many games to work properly.

The developer of the best emulator (Stella) is still finding little incompatibilities and nuances to iron out, and some classic-era games didn't work 100% properly until relatively recently.
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Offline Kerr Avon

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Re: Mega SG and FPGA Jailbreaking
« Reply #9 on: February 29, 2020, 06:31 PM »
Writing games for the Atari 2600 must have been amazingly finicky and difficult. The console didn't even have any video RAM (video RAM is an area of memory where you create the screen image (and it's contents) that you want to show, and the console automatically copies the contents of the video RAM to the real TV screen). Instead you had to keep track of what part of the TV screen was being written to at that particular tiny fraction of a second, and manually change the colour that was being written when the update 'cursor' was at the parts that you wanted to show a different colour.

Add that to the tiny amount of actual RAM (128 bytes), a not too fast processor, and games that had a very severe size limitation imposed by the cartridge formats of the day (usually 2 or 4 kb, though later games had more), and it's amazing that the 2600 had games as good as it did.

The most impressive program feat I can remember from those days though, was on the 1 kilobyte version of the ZX81, where someone has written a full Chess program (more or less). The ZX81 read it's programs from cassette, and used part of it's 1kb of RAM for screen memory and the system variables (unless you didn't need the latter, and so could overwrite them with your own code), so the Chess program wasn't even a full kilobyte in length, amazingly. It had no graphics, just a letter for each chess, and [to quote Wikipedia] "1K ZX Chess's code takes up only 672 bytes in memory, but implements chess rules except for castling, promotion, and en passant, including a computer opponent."

Utterly amazing.

Offline nuu

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Re: Mega SG and FPGA Jailbreaking
« Reply #10 on: February 29, 2020, 10:31 PM »
Yes, the video chip isn't doing all the work like on NES so the game has to draw each frame manually. The only time for actual game logic is the tiny period between frames when the TV is retracing the beam to the upper corner again (VSYNC/VBLANK). This is the reverse of how you do it on other systems like the NES, where the video chip is doing the hard work of drawing the frame leaving the game free for game logic during the frame period, and only having to send data for graphic updates for the next frame during the tiny VBLANK period.

So emulating the Atari hardware accurately is necessary for things to work while on NES you can get away with approximating the video chip's work and still get most games to work.


The ZX80 computer is even worse as it has almost no video hardware at all. The CPU does ALL the work, which makes the screen blink every time anything is updated to make time for the CPU to do any kind of logic.
« Last Edit: February 29, 2020, 11:09 PM by nuu »

Offline brianvgplayer

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Re: Mega SG and FPGA Jailbreaking
« Reply #11 on: March 03, 2020, 11:06 PM »
Did the JB Nt mini already have a 2600 core? I know it had a 7800 core.