1983
The 731 included a mini-plotter with 4 pens and a cassette-drive.
There were also the MZ721 equipped only with
the cassette-drive and the cpu-only MZ700.
Sharp called the MZ-series CLEAN-computer.
That means that you have to load a OS or a programming-
language before you can do anything.
The advantage is the fact that you can use the full memory,
in this case 64K.
(The picture shows the 731 with a funny 2.8inch
floppy drive called Quick-disc)