The code can be exercised (by the IDE), by using "call" to invoke /pcf2123 for initialization, sdt to set the date and rdt to read the date. Values for "sdt" can be pushed onto the node's stack by using "lit". I used a logic analyzer to look at the results.
There was a lot of setup to get this going, and I am not going to cover that right now.
I need to get the plumbing (wiring) right. Getting 1 node to talk to another is not as intuitive as I hoped. I also fear that the IDE gets critically in the way (hook et al can wipe out your node's RAM when creating paths). This will mean that the IDE will be less useful for stuff that is very node position dependent (i.e. GPIO nodes).
I don't fully grok the inter-node comms yet. In particular, I am not sure how to "push" numbers from one node to another. The IDE does this fine with "lit", but if my node isn't wired by the IDE all I have is "warm/await". The apparent exemplar for passing values between nodes is to explicitly have the target node "fetch" values from the port. Unfortunately, as you can see from the code below, I am out of room (0x40 max words per node and I am at 0x3d). I could shrink the code a bit more, but...