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  • Joined: 07 May 2023
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Need Help Understanding Master System Capabilities
Post Posted: Sun May 07, 2023 8:20 pm
Attention all Master System nerds! I need your help. I have some questions I need answered. Explanation underneath if interested.

Here's what I need to know.

- Would a Sega Card be able to function in conjunction with a cartridge game, similar to Lock-On Technology (TM)?

- Would it be possible to create something similar to Sonic 3D Blast's ""Secret Level Select"" by halting gameplay and sending the player to a hidden screen whenever a glitch is detected?

- Could the game's title screen be temporarily changed as part of a puzzle?

- Is it possible for the game to know when it has been turned off without saving?

I do not own a Master System (shh, don't tell anyone) and I cannot program, but I have started a project that revolves around creating a fake Master System game as part of a found footage styled video. Being accurate to the capabilities of the system is of the utmost importance to me, because I Like Making Things Way More Difficult Than They Need To Be.

If you've never heard of OneShot, its a indie game released for computers in 2014, remade and improved for computers in 2016, and reremade and kind of crippled on console just the other year.

I got the idea to make a found footage video with the concept "What If OneShot Was Released For The Master System?" I already understand the limits of its graphics pretty well, as well as general abilities of systems from the time, but I need to know what exactly the system is capable of in order to sort of transfer OneShot's 4th wall breaking puzzles to the best of my ability.



If anyone could answer any of these questions it would be greatly appreciated. Thanks in advance!
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Post Posted: Sun May 07, 2023 9:41 pm
Yes to all of them.
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Post Posted: Sun May 07, 2023 9:49 pm
Maxim wrote
Yes to all of them.


oh okay awesome!
unrelated question. howd you get to know all that? did you like, spend years messing around getting to know the system, or were you a developer back in the day?
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Post Posted: Mon May 08, 2023 6:34 am
More years messing around than the entire lifetime of the system. I was just a kid back in the day.

Some technicalities:

- Software can swap between card, cart, BIOS and expansion port at any time. In fact, that’s how the BIOS works. With some extra helpers on the card and cartridge, you could even enable them both at the same time. However you would still only have a 48KB address space to “see” the data. The Sonic and Knuckles “lock-on” extension was dealing with a rather larger address space which makes things a little simpler.

- The Master System doesn’t have error handlers like the Mega Drive so glitches are more likely to lead to a reset. However if we assume they are likely to lead to executing “empty” space then we can fill empty space with a “rst” opcode that leads to an error handler. I wrote code for this in a game I made but it was never really useful :)

- Changing something in code is easy.

- 8-bit era cartridge saves were generally done with on-cartridge battery-backed RAM. This is super fast to access so you could easily set a “dirty” flag and then clear it upon “clean” save.
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Post Posted: Mon May 08, 2023 8:45 am
RealSMSOwnerForSure wrote
- Is it possible for the game to know when it has been turned off without saving?


Only if the game had code in place to exactly detect that. as Maxim said, you need the game to write some 'dirty' flag to SRAM to signal that there have been updates after the last save. I suspect no existing game does that, you might want to keep this in mind.
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Post Posted: Mon May 08, 2023 9:50 am
The idea seems to be about whether a Master System game could have behaviour that could help it be like the OneShot inspiration, eg knowing if you turned it off or if a card was inserted, and having that affect the game on the cartridge.
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Post Posted: Mon May 08, 2023 2:01 pm
okay thanks a bunch guys
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