two flash chips and remove original bios

[johnriper]

can i completly remove original dreamcast bios and install two flash chips, one with region free bios and one to boot dreamshell from sd?
thanks.

[cybdyn]

why not

[SWAT]

Of course you can do it!

[johnriper]

(08.06.2012 12:43)SWAT писал(а):  Of course you can do it!

can i have a little help with scematics?
in both chips do i solder together pin 1, 23 and 44 and select to boot with seperate 12 pin?
thanks.

[segadreamcaster]

(08.06.2012 18:28)johnriper писал(а):  

(08.06.2012 12:43)SWAT писал(а):  Of course you can do it!

can i have a little help with scematics?
in both chips do i solder together pin 1, 23 and 44 and select to boot with seperate 12 pin?
thanks.

I have done this and it is possible but can be very problematic unless you are good at this kind of thing. I consider myself average and managed to kill two boards doing the double mod, whilst I had no issues with the normal piggy back mod, done that a few times now.

To be honest, now that I ave done it I have found it to be less useful than I anticipated. Many ISO's just won't run so well from the bios boot. For example I can't get the Atari 7800 emu working properly from a bios boot or the Amstrad emu, which runs without sound, but they both work fine if booting Dreamshell with a disc. Similary, a lot of official games don't work well either. Hopefully these issues will be resolved in the future, which would make it very worthwhile having a dual flashable bios.

In terms of the schematics, you can simply solder all legs (except leg 12) to the board and then join all legs of the second chip (except leg 12). Legs 1 & 44 apparently have no use so you can have them up or down..it doesn't really matter. After that just follow the usual guide and select with a switch using the leg 12 on each chip

Hope this helps

Cheers

[johnriper]

i have completed the mod and everything works great, thanks for the help.

[segadreamcaster]

(03.07.2012 10:33)johnriper писал(а):  i have completed the mod and everything works great, thanks for the help.

Excellent, glad you did it ok...enjoy

[vincent]

would like to perform the same but have doubts regarding pin 44 (write enable):

shouldn't there be a switch with which you can select which of the two flash chips has write enabled?
i mean: is there not the possibility of damiging the flash chip when you put high on /we without chip enabled (/ce)?

[megavolt85]

(30.08.2015 13:27)vincent писал(а):  i mean: is there not the possibility of damiging the flash chip when you put high on /we without chip enabled (/ce)?

No