I've got an SD card adapter on the way, and am thinking of making my dreamcast triple BIOS, so that I can have original PAL BIOS, region-free BIOS and boot dreamshell from SD card BIOS. The tricky part here is the switch for the chip selects. I could use more than one switch, but what I am thinking is that if I use a DPDT switch with a central off position, I can use one half of the switch as normal to switch which of 2 chips gets ground to it's CS (the CSs on these 2 chips have pull-up resistors as normal), and wire the third chip with a pull-down resistor to ground (instead of pull-up to VCC as is normal), and have the other half of the switch give it VCC whenever it is not in the central position. This isnt the prettiest schematic I've ever drawn, but you get the idea. CS1/2/3 are the chip selects from the flash chips (pin 12), the resistors are 10k. This should work right? Wanted to chekc there isn't a better way or something I've missed before I do this!
