Back about the time these were coming off sale, I found a shop in London that was remaindering them very cheaply. I bought one and took it into the Government Department for which I then worked. Jealous eyes, then a very senior person had a word with the Clerk of Stationery, and a cab was dispatched to clear out the shop. They lasted in intensive Government use for quite a number of years, only finally being overtaken by much more modern laptops. They were light and the battery would last all day. And there was a very portable printer $ battery again$ that went with them.
The later snag was that they were CPM, whereas the desktop machinery was MSDOS by then, so transferring texts across was a bit of a fag $though it could be done$.
I later used mine to calculate race results at a dinghy sailing club, though it was a bit slow for real-time work of that kind.

The Epson PX-8 was actually quite impressive. Besides running for up to three hours on it's batteries (with the battery backpack), it could also play and record minicassettes, in data or voice mode.

The cartridges were actually more akin to ROM chips. You had to open the bottom of the case, and swap them out. It also featured a RAM drive with it's RAM, and you could access the data minicassette like a regular disk (albeit slower) through the on-board CP/M.

All in all, pretty nice machines, and light too. I still own mine, and it runs beautifully save for the dead batteries.

In Japan two models were sold the HC-80 and the HC-88. The HC-80 was less expensive and did not have the Kanji ROMs. It looks like the keyboard was slightly different for the HC-88 whereas the HC-80 keyboard was very much like the PX-8.