I have s3b and s3c main units.
type Handheld computer
country UK
year 1993
os epoc
cpu 16-bit NEC V30H
speed 7.68 MHz
ram 256 KB (s3b) / 2MB (s3c)
rom 1 MB
graphic 480×160
colors 2
sound Membrane speaker
power two AA battery
ports serial, ssd slot (2)