Dr Jefyll

Nice work, Wickeycolumbus! I stopped in to say hi after seeing a post about your project on the forum at 6502.org. http://forum.6502.org/viewtopic.php?f=12&p=33888#p33888 No doubt LOTS of other folks have noticed, too, since your diode ROM was featured on Hackaday! I hope you're enjoying the well-deserved attention. BigO mentioned taking the diode ROM concept into the third dimension, and that prompted me to share some photos. This ancient project of mine has a ROM that's both 3D and manually alterable! Every diode has a SPST switch in series with it. Its capacity is eight 12-bit words (plus two 5-bit words, but who's counting). There are two 12-bit buses that feed a 12-bit counter and a 12-bit comparator, implemented in CMOS (which is very well suited for interfacing with diode logic). What it all does is count encoder pulses for machine control, and altering the ROM sets various distances the motor has to move. In case anyone's wondering, this project predates microcontrollers. Although it has peripherals that can digest 12-bit values, the "CPU" on this board is a one-bit design similar to this: http://hackaday.com/2014/04/20/the-computer-without-a-cpu/#comments cheers, Jeff http://LaughtonElectronics.com