Sega/Mega CD bios mod

[PCEngineHell]

Granted I am sure this info is around on the net in different places, but I think most of it covers the multi-bios that has the 3 regions on one chip. If you are only interested in US/JP or UK/JP region swap however, then this will get you where you need to be as far as Model 1 and Model 2 systems go. Whatever bios you use it will need to be byte swapped before being burned off.

If you don't have an eprom programmer capable of doing 40 pin chips you will have to find someone out there who can flash said eproms for you. A member here did it for me, but I am not sure if he is ok with tossing his name out there for this stuff. But if he wants to chime in I can confirm that he is 100 percent reliable concerning the chip/eprom service.

Concerning the actual mod, some people prefer on the model 2 to take the pussy way out and slap a socket over the original bios and just slather hot glue all over the back side and hope it all holds connection. I did not do this, instead opting to strip down a 40 wire ide cable and do a 40 wire solder job leading from the original bios solder joints to the pins on a 40 pin socket. However you plan to do it is up to you.

/segacdregionmod.png

Also, as my understanding is people do this a lot by mistake. If you do this on a Model 2 on pin 20 of the original bios, rip it up off the pcb or destroy the solder contact from excessive burning on the pcb when trying to sever connection, don't lose hope. Just stop and take a breather.

Next take a close look around the bios. For sure on at least one revision of the pcb, on the top side of the pcb there is a trace that leads from said solder contact to under the bios on down to a via/through-hole nearby, so you can make a repair. It is possible they revised the placement or where this trace leads to on different revisions of the pcb, so just pull out that magnifying glass and led light and take a close look around.

As with most any trace repair due to similar damage where you don't actually need to repair/tin and relace the trace itself with copper/solder, you can take a couple of thin long threads out of a wire, twist them together tight and lace them completely with solder to make it hard, insert in the via on other end of trace that lead to damaged joint, and heat both ends. Then trim it down to make a new solid solder joint connection with the ability to solder on to it from either side of the pcb. After you solder your wire to this new joint, if you want to reinforce it you can cover the area with epoxy/enamel.

[bust3dstr8]

I can supply the bios for people that need one. $9 shipped with a socket.

Also if you can remove your original bios cleanly and install the socket, I can program the chip to work with an less involved installation method.

[PCEngineHell]

Yep, bust3dstr8 is who did the eprom for me. You could also do the multi-bios on one eprom method if you want all 3 regions supported or whatever. He can program that also. And per what he said above about removing the original bios, if you have a Model 1 Cd system that is the easiest for removing the entire chip.

[OGHUGO]

Granted I am sure this info is around on the net in different places, but I think most of it covers the multi-bios that has the 3 regions on one chip. If you are only interested in US/JP or UK/JP region swap however, then this will get you where you need to be as far as Model 1 and Model 2 systems go. Whatever bios you use it will need to be byte swapped before being burned off.

If you don't have an eprom programmer capable of doing 40 pin chips you will have to find someone out there who can flash said eproms for you. A member here did it for me, but I am not sure if he is ok with tossing his name out there for this stuff. But if he wants to chime in I can confirm that he is 100 percent reliable concerning the chip/eprom service.

Concerning the actual mod, some people prefer on the model 2 to take the pussy way out and slap a socket over the original bios and just slather hot glue all over the back side and hope it all holds connection. I did not do this, instead opting to strip down a 40 wire ide cable and do a 40 wire solder job leading from the original bios solder joints to the pins on a 40 pin socket. However you plan to do it is up to you.

/segacdregionmod.png

Also, as my understanding is people do this a lot by mistake. If you do this on a Model 2 on pin 20 of the original bios, rip it up off the pcb or destroy the solder contact from excessive burning on the pcb when trying to sever connection, don't lose hope. Just stop and take a breather.

Next take a close look around the bios. For sure on at least one revision of the pcb, on the top side of the pcb there is a trace that leads from said solder contact to under the bios on down to a via/through-hole nearby, so you can make a repair. It is possible they revised the placement or where this trace leads to on different revisions of the pcb, so just pull out that magnifying glass and led light and take a close look around.

As with most any trace repair due to similar damage where you don't actually need to repair/tin and relace the trace itself with copper/solder, you can take a couple of thin long threads out of a wire, twist them together tight and lace them completely with solder to make it hard, insert in the via on other end of trace that lead to damaged joint, and heat both ends. Then trim it down to make a new solid solder joint connection with the ability to solder on to it from either side of the pcb. After you solder your wire to this new joint, if you want to reinforce it you can cover the area with epoxy/enamel.

Are you stupid?  This is not the sega forums..  I suggest you go here. 
http://16bitgamer.forumotion.ca/

[PCEngineHell]

This is awesome. I'm glad you are willing to share tech info with this forum, making sure to give back as much information as possible, since I know many members here play on and do mods for more then just one fucking system type. Now if only I could figure out some way to give back to this community without just offering to give free head and reach arounds after trying to hassle Bernie with the classic scammer shake down.....

QFT.

[OGHUGO]

You need to go here with that idiot.. 
 http://16bitgamer.forumotion.ca/

[PCEngineHell]

I cant wait to use this 100 percent free mod info you posted on some of my future ebay sales.

IKR?

[wolfman]

There are times where this forum is just hilariously funny.

[LameKat]

How about an S-1/S-10 bios?

[PCEngineHell]

How about an S-1/S-10 bios?

Hit up the guy behind that video and see what he says. Personally I have no interest in the Laseractive, so I wouldn't be able to help you there.

[BlueBMW]

The bios chips in the Laseractive pacs are socketed so I suspect it wouldnt be too hard to physically do.  I know its been done before.  I dont know how complicated it would be to dump the existing rom images and do similar.... any interest in trying bust3dstr8?  The only other issue is where to mount a switch....  there really isnt a good place on a pac.  I could see maybe a recessed switch mounted near the back of the pac that could be switched while the pac is removed...

[LameKat]

That's exactly the placement I was thinking.

[bust3dstr8]

I am surprised there aren't any dumps of the PAC bios yet.  I just shipped back a PAC-S1 and only have a S10 on hand.  If I get the files and Lamekat buys me a 12 of Newcastle...we could get a PAC setup with a switchless dual bios in an afternoon.

[PCEngineHell]

This you mean, Mega-LD 1.05 BIOS? DL link:

http://www.sendspace.com/file/02r66v

Use the "   Click here to start download from sendspace" link to grab the file.

[PCEngineHell]

So, looking around a bit I did not spot any other Pac bios dumps, so I guess the one I linked to above is all there is right now that is dumped for public consumption.

[BlueBMW]

Ive seen 1.01, 1.02, 1.04 and 1.05 on various pacs.  They are region specific but the version numbers dont seem to reflect which region.   I know most of the US ones Ive seen have been 1.04  and most of the JP ones 1.02   but thats not true 100% of the time.

[bust3dstr8]

I found two on Emuparadise listed as 1.02, but the internal header reads:

1993.APRMEGA-LD BOOT ROM 03/29-1993     17:00      0.98 MEGA-LD BOOT ROM                                BR 000001-0.985J               


Maybe a proto version listed as 1.02? 
Am I wrong or are versions less then 1 usually reserved for beta builds and pre-release items?

[PCEngineHell]

I found two on Emuparadise listed as 1.02, but the internal header reads:

1993.APRMEGA-LD BOOT ROM 03/29-1993     17:00      0.98 MEGA-LD BOOT ROM                                BR 000001-0.985J               


Maybe a proto version listed as 1.02? 
Am I wrong or are versions less then 1 usually reserved for beta builds and pre-release items?

Interesting, drop me a pm with links to them when you get a chance, so I can add them to my bios folder. Don't really need them, but I try to save that stuff when I come across it regardless in case others need it.

[BlueBMW]

Any recommendations on how to dump the chips themselves?  I think ive got a chip reader/writer that can accept them.

[bust3dstr8]

Any recommendations on how to dump the chips themselves?  I think ive got a chip reader/writer that can accept them.

Read as 27C1024 or 27C210> Byte swap buffer > Save buffer as Mega_LDxxx.bin

Sega Bios are here  http://www.emuparadise.me/Sega_Genesis_-_Sega_Megadrive_ROMs/Games-Starting-With-Numbers/6