MiSTer FPGA Forum

Just wanted to see what everyone thinks about adding support for the system BIOS.


For those who aren't aware of it's purpose, it was an attempt by Sega to prevent unlicenced 3rd party developers from creating games. If the word "SEGA" isn't written to a certain address in memory within a specified amount of time, it shuts down the VDP.

I like the familiarity of seeing this on startup but practically, homebrew authors wanting to use MiSTer as a testing platform would find their game would work fine until they tried it on a real Megadrive with the TMSS BIOS.

Most emulators support it but not all implement it correctly.

I personally think for accuracy's sake it's worth adding, even if it's only enabled if the BIOS file is present. Would anyone else agree?

I may have a go adding it, I'm still learning though. If it's acceptable of course.

From my understanding, it loads into cartridge space to show it's splash screen above, then puts itself into RAM and executes from there, re-enables the first 2kb of cartridge space to do it's checks then once it's done it triggers the reset vector.

Further to this, for anyone interested, there is some interesting discussion on it's use in the system here:

http://151.236.14.55/byuubackup2/viewto ... =1229.html

I would like it too...

Yeah, it’s not a “gotta have it!” for me, but I would certainly love to see it! That screen is very nostalgic.

+1, for this: "homebrew authors wanting to use MiSTer as a testing platform would find their game would work fine until they tried it on a real Megadrive with the TMSS BIOS."

The TMSS screen is not very nostalgic for me at all. It is very annoying. I purchased the Genesis on launch (non-TMSS) and in later years purchased a model 2 and was ticked that it had this stupid license screen...not to mention it blocked some EA games such as Budokan and Populous (and I think Zany Golf) from working. Nope, I don;t want to see it again

eightbit wrote: ↑Fri Jul 24, 2020 6:00 am The TMSS screen is not very nostalgic for me at all. It is very annoying. I purchased the Genesis on launch (non-TMSS) and in later years purchased a model 2 and was ticked that it had this stupid license screen...not to mention it blocked some EA games such as Budokan and Populous (and I think Zany Golf) from working. Nope, I don;t want to see it again

When I implement it then, you can turn it off

retrorepair wrote: ↑Fri Jul 24, 2020 7:37 am

eightbit wrote: ↑Fri Jul 24, 2020 6:00 am The TMSS screen is not very nostalgic for me at all. It is very annoying. I purchased the Genesis on launch (non-TMSS) and in later years purchased a model 2 and was ticked that it had this stupid license screen...not to mention it blocked some EA games such as Budokan and Populous (and I think Zany Golf) from working. Nope, I don;t want to see it again

When I implement it then, you can turn it off

Lol...I guess your right. From a preservation perspective it is good to have the option.

Just for curiosity, is tmss shown also with megacd attached in both modes 0/1?

Lisko wrote: ↑Sat Jul 25, 2020 9:14 am Just for curiosity, is tmss shown also with megacd attached in both modes 0/1?

If a cartridge is inserted, yes. If not, no.

I would like a TMSS option because my real Model 1 has it and it would be rad.

I know a few games don't work on TMSS consoles, but do any games requires TMSS?

Definitely not, or they'd all break on early (rev 1 and 2) consoles.

I have the TMSS ROM set as my boot.rom to kinda replicate the real thing. It loads just fine, but it causes some annoying flickering as it sees itself as a cartridge and loads itself infinitely. is it possible to modify the ROM to disable the cartridges load so it just stays on the copyright text?

jlancaster86 wrote: ↑Thu Dec 23, 2021 6:30 am I have the TMSS ROM set as my boot.rom to kinda replicate the real thing. It loads just fine, but it causes some annoying flickering as it sees itself as a cartridge and loads itself infinitely. is it possible to modify the ROM to disable the cartridges load so it just stays on the copyright text?

I am sure there has to be a way to do so. And this is all more easier said than done as I have only a laymens understanding of this.
Someone with a Emulator with a in-game debugger could perhaps see the code execute in real time and perhaps isolate it.
Once you know what code triggers the check, you can edit it to keep from coming up.