This is the schematic for the CPU board of my TinkerBug 6809 computer. It is basically the board that Frank Wilson designed and that was published in The Computer Journal way back when. I have modified it slightly and added the 74LS138 circuit to allow me to select up to 8 I/O devices. Otherwise it is pretty much Frank's design. I re-wrote the monitor code to suit my needs. I kept the bit-banging code to drive the PIA as a serial port.
Here is the schematic for the ATA/IDE board I am working on. It is still a work in progress and this circuit may change if the need comes up.