I'm not sure about the history of those types of systems. They kinda branch off each other and then get confusing once you start considering PDAs and Programmable calculators. Wearable PCs are neat and yes I have a MA-V and MA-IV from Xybernaut also. I haven't had much time to use them lately but want to play with the V again and see if I can get it to run some vintage games. The IV was too slow to play Hardwar and could honestly barely play Terminal Velocity although it could have been OS related but a 233Mhz system with 64MB RAM and 2GB drive was pretty sweet specs at the time. I actually bought mine in off ebay back in 98 or 99 so I paid something like $1800 for one and $1200 for a Via Wearable Computer (later dubbed flexi-pc). Which honestly I was stoked about the price. Either alone were right around $5000 each (new) and the specs were actually matching my new desktop at work. I brought them into AMD at the time to show off lol people kinda laughed until I told them the system specs and it was faster than most of their desktops and running NT 4.0 just like we were. Ironically I bought them from a competitor company's CEO.. the long(er) story is it was myself and General Dynamics who were the interested parties. I'd never heard of them before then and felt bad for the little company until I checked their website and saw who they were. Afterwards I just hoped I didn't have a missile show up at the house. I won the price but they also carried them after that anyway (obviously Xybernaut had them in mind and so did my seller).
I got a Fujitsu something or other off of T a few years back which is somewhat early for a "wearable" tablet PC (since it has an arm strap and that stylus). I know there was a site I used to see about the history of PDA/portables/wearables or something that had a lot of those firsts listed but I'm not finding it right now.
But yeah, you'd go from wearables, back to tablet (well the term tablet is newer than wearable), to wrist-worn, to PDAs and palm-tops, notebooks and laptops are probably thrown in there, then older would be first portable computers and calculators that could be programmed.. IMHO of course.