Okay, I figured out the immediate problem. Three of the pins on one of the EPROMs have broken off. One was hanging by a thread and fell off when I inspected it. I see no evidence that the pins remain in the sockets so I guess they must have fallen off when I removed the EPROMs to read them in my EPROM programmer. I suppose this suggests that they may have fallen off *before* I read them and that is why your SnapFORTH ROMs don't work. I don't think that's the case though because I'm sure I would have noticed that. Do EPROM (or chip pins in general) get more brittle as they get older?