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I am planning to modify my 1988 Master System to play Japanese games so I don't have to blow $200 on a MK-III. I found out the wiring, but I need to know how to remove the Bios. Do I just need to take out the chip or do I need to do more?

I also was wondering, in a converter, what is the board that goes into the cartridge slot called?

Thanks.

Quote

> I am planning to modify my 1988 Master System to play Japanese games so I don't have to blow $200 on a MK-III.

Are you aware that you'll also have to build a converter for the cartridge-based games, since the western SMS has a different type of connector? (I expect you are, since you mention converters further down...)

Quote

> I found out the wiring, but I need to know how to remove the Bios. Do I just need to take out the chip or do I need to do more?

You don't necessarily have to remove the chip, just disable it by disconnecting pin 20 of the ROM (the "Chip Enable" line). You can simply cut this pin and lift it clear of the board.

Assuming you want to bypass the BIOS entirely, you then have to cut the trace leading to pin 13 of the cartridge connector (and the trace leading to pin 13 of the card connector, if you want to play card-based games). Then, solder a wire link between pin 1 of the 315-5216 IC and pin 13 of the cartridge connector (and another one from 315-5216 pin 1 to card connector pin 13).

If you do connect the card port in this way, this maps both cartridge and card ports to the same "slot", so be careful not to insert both a cartridge and a card at the same time. (Using the 3D glasses is no problem, however.)

The purpose of the wire link is to connect the cartridge (and card) ports to the highest priority slot "enable" signal, previously occupied by the BIOS. So, when the SMS is turned on, instead of running the BIOS initially (which is now disabled), it runs the cartridge (or card) directly.

A few western-only SMS games may not work correctly after this modification, if they assume a BIOS is present, but Mark III/Japanese SMS software should work fine, as should SG-1000/OMV software. (The Mark III and earlier consoles don't have a BIOS, as you probably know.)

Quote

> I also was wondering, in a converter, what is the board that goes into the cartridge slot called?

Just a printed circuit board (PCB), it doesn't have a special name to my knowledge. The part of the board that interfaces with the cartridge slot is called an edge connector.

Mike

SMSReader

Thank you for the help on the BIOS.

I was actually just going to take out the 50-pin connector and wire in a 44-pin edge connector, since I was able to get the wiring from Yujiro's site and translate it.

If I did build a converter, would I be able to use a SMS PCB or would I have to search for a brand new one from an electronics store?

Also, I read about using a 50-44 pin converter with the GG and Master Gear converter. I read something that looks like Silver Cartridges might have a problem running with it. Does anyone know if this is true? The only game I have to test is Rygar (Silver Cartridge).

Quote

> Thank you for the help on the BIOS.

> I was actually just going to take out the 50-pin connector and wire in a 44-pin edge connector, since I was able to get the wiring from Yujiro's site and translate it.

Fair enough, and it would probably be more reliable than using a converter.

Do you know where to get those 44-pin connectors from? I've had enormous difficulty finding a supplier for them, and ended up having to fudge a connector together. (It's a bit Heath Robinson but it works!)

Quote

> If I did build a converter, would I be able to use a SMS PCB or would I have to search for a brand new one from an electronics store?

You can use the PCB from any SMS cartridge if you remove the ROM.

Quote

> Also, I read about using a 50-44 pin converter with the GG and Master Gear converter. I read something that looks like Silver Cartridges might have a problem running with it. Does anyone know if this is true? The only game I have to test is Rygar (Silver Cartridge).

It depends on your GG. The problem with Rygar (and, IIRC, one or two other Mark III games) is that it doesn't have the "TMR SEGA" header at location 0x7FF0 in the ROM. If you have a newer Game Gear with the BIOS (you can tell if it has a BIOS because it will display a blue screen with "Produced By Or Under License From..." before each game) then it will check for the header and refuse to run the game if it isn't found.

If your GG is an older one with no BIOS, you'll have no problem running those games.

Mike

Thanks for the info once again.

www.allelectronics.com carries 44 pin connectors, but they might ship only to the US, I'm not sure.

Do you know if the blue GGs have a BIOS? I haven't seen a GG without the Produced By or Under License From Sega Enterprises screen.

For bulding a converter, do you solder directly to the pin or at the end of a pin's trace?

Also, and SMSReader question:

I plan to build one of these later this summer. I noticed that in the picture a European power supply was being used. Is the US power supply compatible?

Quote

> Thanks for the info once again.

> www.allelectronics.com carries 44 pin connectors, but they might ship only to the US, I'm not sure.

Cheers, I'll have a look.

Quote

> Do you know if the blue GGs have a BIOS? I haven't seen a GG without the Produced By or Under License From Sega Enterprises screen.

I'm not sure, but I would hazard a guess that all GGs other than the very earliest (1990/91) models have a BIOS. Sega started shipping Genesis/Mega Drive consoles with BIOSes in late 1991, so it would make sense if they started doing the same with the GG around this time.

This is pure conjecture, though. The only things I have to go on are a very early GG (1991) which doesn't have a BIOS, and a very late one (Majesco, 2000), which does.

Quote

> For bulding a converter, do you solder directly to the pin or at the end of a pin's trace?

I generally solder to the end of the trace if possible, rather than directly to the pins of the edge connector. It's very easy to mess up the edge connector otherwise.

Quote

> Also, and SMSReader question:

> I plan to build one of these later this summer. I noticed that in the picture a European power supply was being used. Is the US power supply compatible?

Yes, certainly! You can use the power supply from a US SMS (1 or 2), or Genesis 1.

Mike

Author	Message
B Joined: 22 Dec 2004 Posts: 233 Location: Boston, MA, USA	Removing the SMS Bios Posted: Fri Jul 19, 2002 10:59 pm
	I am planning to modify my 1988 Master System to play Japanese games so I don't have to blow $200 on a MK-III. I found out the wiring, but I need to know how to remove the Bios. Do I just need to take out the chip or do I need to do more? I also was wondering, in a converter, what is the board that goes into the cartridge slot called? Thanks.

Mike G Joined: 21 Apr 2000 Posts: 598 Location: Newcastle upon Tyne, England	Posted: Sat Jul 20, 2002 8:35 am
	Quote > I am planning to modify my 1988 Master System to play Japanese games so I don't have to blow $200 on a MK-III. Are you aware that you'll also have to build a converter for the cartridge-based games, since the western SMS has a different type of connector? (I expect you are, since you mention converters further down...) Quote > I found out the wiring, but I need to know how to remove the Bios. Do I just need to take out the chip or do I need to do more? You don't necessarily have to remove the chip, just disable it by disconnecting pin 20 of the ROM (the "Chip Enable" line). You can simply cut this pin and lift it clear of the board. Assuming you want to bypass the BIOS entirely, you then have to cut the trace leading to pin 13 of the cartridge connector (and the trace leading to pin 13 of the card connector, if you want to play card-based games). Then, solder a wire link between pin 1 of the 315-5216 IC and pin 13 of the cartridge connector (and another one from 315-5216 pin 1 to card connector pin 13). If you do connect the card port in this way, this maps both cartridge and card ports to the same "slot", so be careful not to insert both a cartridge and a card at the same time. (Using the 3D glasses is no problem, however.) The purpose of the wire link is to connect the cartridge (and card) ports to the highest priority slot "enable" signal, previously occupied by the BIOS. So, when the SMS is turned on, instead of running the BIOS initially (which is now disabled), it runs the cartridge (or card) directly. A few western-only SMS games may not work correctly after this modification, if they assume a BIOS is present, but Mark III/Japanese SMS software should work fine, as should SG-1000/OMV software. (The Mark III and earlier consoles don't have a BIOS, as you probably know.) Quote > I also was wondering, in a converter, what is the board that goes into the cartridge slot called? Just a printed circuit board (PCB), it doesn't have a special name to my knowledge. The part of the board that interfaces with the cartridge slot is called an edge connector. Mike SMSReader

B Joined: 22 Dec 2004 Posts: 233 Location: Boston, MA, USA	Posted: Sat Jul 20, 2002 1:02 pm
	Thank you for the help on the BIOS. I was actually just going to take out the 50-pin connector and wire in a 44-pin edge connector, since I was able to get the wiring from Yujiro's site and translate it. If I did build a converter, would I be able to use a SMS PCB or would I have to search for a brand new one from an electronics store? Also, I read about using a 50-44 pin converter with the GG and Master Gear converter. I read something that looks like Silver Cartridges might have a problem running with it. Does anyone know if this is true? The only game I have to test is Rygar (Silver Cartridge).

Mike G Joined: 21 Apr 2000 Posts: 598 Location: Newcastle upon Tyne, England	Posted: Sat Jul 20, 2002 3:09 pm
	Quote > Thank you for the help on the BIOS. > I was actually just going to take out the 50-pin connector and wire in a 44-pin edge connector, since I was able to get the wiring from Yujiro's site and translate it. Fair enough, and it would probably be more reliable than using a converter. Do you know where to get those 44-pin connectors from? I've had enormous difficulty finding a supplier for them, and ended up having to fudge a connector together. (It's a bit Heath Robinson but it works!) Quote > If I did build a converter, would I be able to use a SMS PCB or would I have to search for a brand new one from an electronics store? You can use the PCB from any SMS cartridge if you remove the ROM. Quote > Also, I read about using a 50-44 pin converter with the GG and Master Gear converter. I read something that looks like Silver Cartridges might have a problem running with it. Does anyone know if this is true? The only game I have to test is Rygar (Silver Cartridge). It depends on your GG. The problem with Rygar (and, IIRC, one or two other Mark III games) is that it doesn't have the "TMR SEGA" header at location 0x7FF0 in the ROM. If you have a newer Game Gear with the BIOS (you can tell if it has a BIOS because it will display a blue screen with "Produced By Or Under License From..." before each game) then it will check for the header and refuse to run the game if it isn't found. If your GG is an older one with no BIOS, you'll have no problem running those games. Mike

B Joined: 22 Dec 2004 Posts: 233 Location: Boston, MA, USA	Posted: Sun Jul 21, 2002 8:29 pm
	Thanks for the info once again. www.allelectronics.com carries 44 pin connectors, but they might ship only to the US, I'm not sure. Do you know if the blue GGs have a BIOS? I haven't seen a GG without the Produced By or Under License From Sega Enterprises screen. For bulding a converter, do you solder directly to the pin or at the end of a pin's trace? Also, and SMSReader question: I plan to build one of these later this summer. I noticed that in the picture a European power supply was being used. Is the US power supply compatible?

Mike G Joined: 21 Apr 2000 Posts: 598 Location: Newcastle upon Tyne, England	Posted: Mon Jul 22, 2002 4:55 pm
	Quote > Thanks for the info once again. > www.allelectronics.com carries 44 pin connectors, but they might ship only to the US, I'm not sure. Cheers, I'll have a look. Quote > Do you know if the blue GGs have a BIOS? I haven't seen a GG without the Produced By or Under License From Sega Enterprises screen. I'm not sure, but I would hazard a guess that all GGs other than the very earliest (1990/91) models have a BIOS. Sega started shipping Genesis/Mega Drive consoles with BIOSes in late 1991, so it would make sense if they started doing the same with the GG around this time. This is pure conjecture, though. The only things I have to go on are a very early GG (1991) which doesn't have a BIOS, and a very late one (Majesco, 2000), which does. Quote > For bulding a converter, do you solder directly to the pin or at the end of a pin's trace? I generally solder to the end of the trace if possible, rather than directly to the pins of the edge connector. It's very easy to mess up the edge connector otherwise. Quote > Also, and SMSReader question: > I plan to build one of these later this summer. I noticed that in the picture a European power supply was being used. Is the US power supply compatible? Yes, certainly! You can use the power supply from a US SMS (1 or 2), or Genesis 1. Mike

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