This project is for owners of a SEGA ST-V (SEGA Titan Video) PCB.
The ST-V is a cart based system which allows you to change game by just inserting another game cartridge. All cartridges are the same physically. There is no keyed connector protection like on the Taito F3 motherboard, where a Japanese cart will only fit a Japanese motherboard.
On the ST-V it's the BIOS on the motherboard which controls the region selection. The following types of cart exist:
Instead of buying an extra motherboard to make sure you can play all your games in the language you desire, you can just change the BIOS on the PCB.
Inside each game cart there is region string. The region string consists of 4 characters. The possible characters are:
Inside the BIOS there is a region character (offset 0x809). It contains the letter 'J', 'U', 'E' or 'T'. When the PCB is powered the BIOS verifies that the region character can be found in the region string stored in the cart. Failure to find this will prevent the game from starting and a suitable error message will be displayed.
One solution is to burn a copy of an alternate BIOS into a 27C400 EPROM. To save wear and tear on the chip socket you may want to buy a ZIF (Zero Insertion Force) socket as well.
An even simpler solution is to burn two ROM images into an EPROM and then use a technique called bank switching to select between the two of them.
If your ST-V mother board is equipped with an EPROM of type 27C4096 (or equivalent) you cannot make a dual BIOS. The reason for this is that the 4 Mbit (256K x 16-Bit) EPROM is not available in 8Mbit. The only solution is to buy a ZIF socket, burn the alternate BIOS image into another 27C4096 and switch manually.
The ST-V BIOS image is 524288 (0x80000) bytes long. This means that one needs 18 address lines to address the entire image. If one has 19 address lines one can address 1048576 (0x100000) bytes or twice the amount of memory.
The following drawing shows two images which are stored in memory of a 27C800 EPROM. This device is capable of storing 1Mbit or 1048576 bytes of data.
By using 18 address lines we can address up to 0x080000 i.e the image. By using 19 address lines and setting the topmost bit (A18) to 0 we can still only address 0x080000 bytes. If we set the topmost bit (A18) to 1 we will start accessing the image and this image only!
This technique is called bank switching. By changing the address of the upper address bit we will effectivly switch banks. By storing two BIOS images in a 27C800 EPROM we can switch between them by setting address line A18 high or low.
So in order to get a dual BIOS all you need to do is to concatenate two BIOS images, burn them to a suitable EPROM and install a simple switch.
To determine which BIOS images to burn you might want to compare the list below against the games you own.
Here is a list of ST-V games and which region they will operate in. This list is not a complete list of all ST-V games.
|BAKU BAKU ANIMAL||J|
|DIE HARD ARCADE||UET|
|GOLDEN AXE DUEL||JTUE|
|GROOVE ON FIGHT||J|
|INTRO DON DON||J|
|MARUCHAN DE GOO||J|
|OJAMA THE WORLD||J|
|PUYO PUYO SUN J||J|
|SPORT FISHING 2||J|
|SPORT FISHING 2||UET|
The only game on this list which requires an USA BIOS is "Super Major League".
Do not email me asking where to find these images. All such mails will be deleted. Use your favourite search engine instead.
I take no responsibility whatsoever for any damage you might cause to your hardware, yourself or your surroundings when making this BIOS.
If you don't have the expertise to make your own dual BIOS, you can order one from JammaBoards.
I do not sell or manufacture these ST-V Dual BIOS's. So please don't ask me to make or sell you one.
Here is a list of all the known ST-V BIOS images and their CRC32's:
|20091.bin||0x59ed40f4||Japan (Alt 2)|
Pins 1 & 42 are supposed to be outside the socket!
"The future of ST-V rests upon our work and your work"
(Text found inside BIOS image)