The Psion Organiser was Launched in 1984 as the "world's first practical pocket computer". It was based on an 8-bit Hitachi 6301 processor running at 0.9 MHz with 4 kB of ROM and 2 kB of RAM and had a single-row, monochrome LCD screen. This was followed up by the Organiser II in 1986 with a better keyboard and display and a much larger ROM. It eventually came in three flavours: the CM Model with either 8 KiB, XP Model with 16 or 32 KiB and the LZ Model (later) with 32 or 64 KiB (later ) and featured a new single-tasking operating system.
I had an LX64 model in the late 1980s and got involved in developing software in OPL including a project for the Post Office to assist in sorting offices. Sadly I had to leave it behind when I moved jobs but I've always liked it and found it to be one of the most well-made and reliable bits of retri tech around. This one came from eBay as few years ago.