The SDrive-MAX is an excellent hardware addon for the Atari 8-bit range of computers, it can imitate 810 and 1050 floppy disk drives (up to 4 of them) and a 1010 tape drive allowing the loding of ATR/XEX/CAS files on real Atari hardware. It can now also load ATX files with accurate timing.
The SDrive doesn’t work correctly when it is connected to the SIO bus along with other items but Bernd Herale (BigBen) came up with a solution to the problem using a simple protoboard circuit.
This is the over-engineered full PCB version of that solution.
It requires just 2 4.7KΩ resistors and a SN74LS07N buffer IC. I’ll let the pictures do the work of describing how it all fits together.
Update: Board version is now V4, I’ve moved the extra row of pins a little to hopefully fit common UNO boards better.
Update: Board version is now V3, I’ve added in an extra row of pins for alternative UNO board layouts and a point to switch SIO pin 10 through or not (If you power your UNO from external power, don’t bridge this point, bridge it if you use your SIO connector to power the SDrive.
Here are all the original images posted by Bernd to document this fix.