Lynx Multi Cart

[mqark]

Please put me on the pre-order list!

 

Great work!

[Zoyx]

This isn't a pre-order thread. This is a cheer on... and perhaps pass-on ideas for the developer thread.

[bdoi]

hi i am interested in one too!!

great work

[myrtlebeachbums]

I'm not kidding when I say I just joined this forum just to say - SHUT UP AND TAKE MY MONEY!

 

I'd love this!

[BILLYonaire]

Very interested!

[Jazzoff2000]

A while back someone mentioned a (much needed) cheat finder - pro action replay thingy - would this still be an option???????

Edited April 21, 2015 by Jazzoff2000

[SainT]

Unfortunately not, the Lynx cartridge is more like a compact flash card than a bus interface like other consoles.

[7800fan]

Isn't most of the ROM loaded into RAM before playing? During the long wait at power on? Any cheat would have to be hacked at ROM itself with a flash cart or installed inside by the CPUs.

 

Someone has done hacking for SMS games and TG-16 games over at Krikzz forum using GGG or via hex editior. I'm sure Lynx ROMs can be hacked for cheat when Lynx flash cart is plentiful.

[lNFERNO]

SainT, this is going to be awesome!, I'm interested in one or two

[Jazzoff2000]

Unfortunately not, the Lynx cartridge is more like a compact flash card than a bus interface like other consoles.

Ah well, even without cheats I'm still keen as... (seems everybody is! haha)

[sage]

Isn't most of the ROM loaded into RAM before playing? During the long wait at power on? Any cheat would have to be hacked at ROM itself with a flash cart or installed inside by the CPUs.

 

No its not. the long wait is decryption and checksumming.

data and code is copied from rom to ram "all the time".

which means, code is swapped in and out, data is read in on demand.

[7800fan]

So can the game ROM be stored unencrypted for faster loading? Or is the ROM required to be encrypted?

[+karri]

So can the game ROM be stored unencrypted for faster loading? Or is the ROM required to be encrypted?

 

That is exactly what we do in new releases. The cc65 contains the smallest possible encrypted loader - 52 bytes. Startup is instant.

 

Another topic is that the rom can contain anything from small snippets of binary code to game levels. So there is no generic cheat module available.

 

You need to open up the Lynx and solder in some add-ons to slow down execution or set breakpoints.

[LX.NET]

the rom is required to be encrypted. The decrypting is part of the Mikey chip's boot code. You can however create a different boot loader and encrypt that as part of the game's rom. Not the entire rom is encrypted. Just the first few blocks. The original Epyx boot loaders do the checksumming. Karri and Shawn and others have reverse engineered everything and created a microloadrr that is now part of the CC65 toolstack.

[jum]

On a related note, just found this very interesting blog on hacking the Lynx "cartridge interface":

 

http://dysfunctionaltechnologies.blogspot.com/2013/01/hacking-atari-lynx.html

 

May be possible to build a simple "ROM emulator" using an Arduino (Mega).

[+karri]

On a related note, just found this very interesting blog on hacking the Lynx "cartridge interface":

 

http://dysfunctionaltechnologies.blogspot.com/2013/01/hacking-atari-lynx.html

 

May be possible to build a simple "ROM emulator" using an Arduino (Mega).

 

It is a well documented experiment. By the way, the mysterious small unknown device in the article is most likely an EEPROM for saving high scores.

[GadgetUK]

Interesting article! I guess if there are games where code is not encrypted it should be possible to 'patch' the ROM for cheats etc. Think most commercial games would be a problem due to overall encryption of large blocks etc - ie. you couldn't just swap an instruction or data byte in the ROM image, unless you decrypt the whole thing, patch it and then encrypt it again. Sounds like CC65 stuff might be 'patchable'?

[Shawn Jefferson]

the rom is required to be encrypted. The decrypting is part of the Mikey chip's boot code. You can however create a different boot loader and encrypt that as part of the game's rom. Not the entire rom is encrypted. Just the first few blocks. The original Epyx boot loaders do the checksumming. Karri and Shawn and others have reverse engineered everything and created a microloadrr that is now part of the CC65 toolstack.

 

Credit where credit is due. It was all Karri and Wookie I believe! All I did was some initial work with Uz's cc65 to get the lynx target going (using mainly the work done by Bastian Schick.) Mainly because I wanted to mess around with the Lynx but didn't like K&R syntax and wanted a more "modern" compiler that I was used to using with the Atari 8-bit. Karri has done some amazing work getting the target usable from there.

Edited April 23, 2015 by Shawn Jefferson

[7800fan]

Wow so much info!

[johannesmutlu]

Is there any interest in a mini-sd driven Lynx multi-cart?

 

I looked into doing this a while back but never got around to going any further. If there's interest I'll see what I can do.

i am very interrested in this concept as i just want to have all games on one cart instead of hunting down and/or swappin those games constandly.

HOWEVER i readed that the sd cart is to slow to transfer data fast enough to read in time bt the lynx such as the bootrom encrytion code,another problem is the lack of a hard reset feature for those roms.

BUT i was thinking we may could overcome these issues,by 1 putting the bootrom encrytion code along with an os menu on the flashcard instead sothat the lynx could just read it without issues while those roms are still just put on the sd card,2 if we want to select a rom, the os menu should just skip the first 100 bytes from each game because these are the encryption bootrom code,wich we no longer need and also just to avoid issues.

3 if this trick will not work,then we are forced to hack those games with the bootrom stripped off.4 or we can just use a cf hich speed cf flashcard instead along with the os menu and roms with their bootroms on it,

5 if rebooting for each game is just required,then i was thinking howabout an special circuit board along with a special os chip wich could lead pin 31 to pin 33 (externaly) once needed to achief a hard reset to be able to reboot the the lynx once needed,hopefully these limitations could be overcome.

[7800fan]

How can SD be too "slow"? Some of the faster SD cards can do read upward of 100Mb/sec (UHS-3 for example), far faster than what Lynx RAM can be written to. Plus most of the games are 512k or less, the entire ROM could have been copied to flash cart's temp SRAM when on flash cart menu, then reboot Lynx to load the game off SRAM.

 

SD card have been used in N64 and 32X flash carts without any issues. Those could easily run circles around Lynx on overall processing power. There's even working Playstation 1 SD adapter to play CD ISO, and that's as much as 600MB or more per disc. (granted, it loads about the same speed as original CD mechanism, 300Kb/sec max which even the pokey class 2 SD will handle fine)

[johannesmutlu]

Yep, I'd be interested. Would it function like the Harmony does on the 2600 or the Everdrive carts work on the Genesis?

[johannesmutlu]

It would be challanging to make a working sd flashcard for the lynx,but in theory,1 if hard reset can be done via a special circuit board along with a special os controlled chip, may it could externaly connect pin 31 to pin 33 to achief a hard reset.

2 or moddifiying those game roms with the encrytion lockout code stripped off to avoid the need of rebooting the system.

3 or let the os menu skip the first 100 bytes from each game ( assuming these 100 bytes are reserved for the security encryption code to boot up the lyn)to avoid rebooting the lynx, instead the os should have it's own bootrom to boot the lynx once during setup.

4 but what if each game has it's own unique bootrom? Then the os software needs to have a data base with all bootroms stored on it instead, sothat when you select a game, that the os links that game to it's correct specific bootrom,along with that possibly hard reset trick mentioned early,, this since the sd cart has a low transfer speed to load the bootrom in time, that's why the os should,ve to do this instead.

5 maybe a high speed trasfer gold plated sd card can be made to make up for it's low speed, in order to transfer the bootrom.in time after selecting a game.

6 If that doesn't work then we got to stick with a cf flash card to get high transfer speed sothat it can load the bootrom in time, again along with that hard reset trick, hopefully this limitation can be ovetcome.

[SainT]

On 5/4/2015 at 5:11 PM, johannesmutlu said:

It would be challanging to make a working sd flashcard for the lynx,but in theory,1 if hard reset can be done via a special circuit board along with a special os controlled chip, may it could externaly connect pin 31 to pin 33 to achief a hard reset.

2 or moddifiying those game roms with the encrytion lockout code stripped off to avoid the need of rebooting the system.

3 or let the os menu skip the first 100 bytes from each game ( assuming these 100 bytes are reserved for the security encryption code to boot up the lyn)to avoid rebooting the lynx, instead the os should have it's own bootrom to boot the lynx once during setup.

4 but what if each game has it's own unique bootrom? Then the os software needs to have a data base with all bootroms stored on it instead, sothat when you select a game, that the os links that game to it's correct specific bootrom,along with that possibly hard reset trick mentioned early,, this since the sd cart has a low transfer speed to load the bootrom in time, that's why the os should,ve to do this instead.

5 maybe a high speed trasfer gold plated sd card can be made to make up for it's low speed, in order to transfer the bootrom.in time after selecting a game.

6 If that doesn't work then we got to stick with a cf flash card to get high transfer speed sothat it can load the bootrom in time, again along with that hard reset trick, hopefully this limitation can be ovetcome.

 

Eh?

 

I use SRAM to avoid any latency issues with reading directly from the memory card (which I think may be possible).

 

You dont need to hard reset, just call the boot ROM again. Has the same effect.

 

So be clear, I have a working solution which just needs refinement. Its not theoretically possible, it works, I have one.

 

I've been finishing off my "manual pick and place" thing recently as I just cant place boards accurately enough to be able to manufacture any quantity by hand. Nearly done -- just waiting for some PVC pipe for the vacuum part then I'll be able to give it a go. I'm hoping with a digital microscope attached to an accurate moving bed with plunging vacuum head I'll be able to place stuff accurately and quickly. I have dreams of making an automated pick and place machine, but I think they'll just remain dreams for quite some time yet.

Edited October 25, 2019 by SainT

[+karri]

Ouch. I know what you mean with assembling small chips. That was the main reason why I stopped doing devflash units.

 

On the other hand if the amount of carts go over 100 pieces you can order the carts assembled and smd soldered for a decent price (99 USD's). I am going that route in the programmers forum using a company called Tinysine.