SS22 was a bidirectional synchronous serial interface to use between computers through their 65c22s (hence the SS22 name) with handshaking. In the early experiments, I found out that unfortunately all makes of the 6522 VIA (including WDC!) have a bug in SR mode 011 where the shift register shifts data in under control of an external shift clock. The bug is discussed on the forum under "Hardware" --> "WD65C22S -- still has "the bug"?" The requirement of the flip-flop to remedy the problem made it more complex than I wanted to go here because of the problem of making the clock line bidirectional so that either end could put out a byte whenever, and at whatever speed, it wanted. So unfortunately, it is basically one direction at a time, determined by the DIP switch setting. The flip-flop does however make it completely reliable to over 1/2 Mbps on this one.