The Epson HX-20: for Business on the Move

Considered to be the world's first true mobile computer[source: https://www.theregister.com/2012/11/02/a_history_of_computing_in_20_objects_part_two?page=2], the HX-20 came from a company better known for the printers which it had been producing for 20 years. 

The HX-20 was first announced in 1981 but wasn't generally available until 1983 - the year of this advert. Also introduced in 1983 was the HX-20's stable-mate, the larger more PC-like (although running CP/M) QX-10, which is shown in the advert alongside one of Epson's printers. 

The portable HX-20 would run for up to 50 hours on rechargeable batteries, came with 16K RAM (which was upgradeable to 32K) and even had an optional acoustic-coupler modem available. 

The display was an LCD capable of displaying 4 rows of 20 characters, giving a total of 120x32 pixels. It ran Epson BASIC on two 614KHz Motorola 6801 CPUs.