I suppose my
Acorn System One is probably my smallest system - two Eurocards,
Sharp PC 1500.
Lovelly little machine :-). I have a couple, along with the
printer/plotter and the RS232 interface. Oh, and the technical manual...
I have the manuals to program the thing in assembler so it definitely
counts as a computer not a programmable calculator (I do regard the
smaller Sharp jobbies as glorified calculators even if they have
BASIC and a full mini-keyboard.
I recently bought a Sharp PC1350, which is one of the 'smaller Sharp
jobbies'. I would claim that's a computer, it can be programemd in
machine code (I have the machine language manual and the service manual),
it's got the tranditional CPU + ROM + RAM + I/O type of architecture,
there's even a built-in CMOS-level serial port (I got the RS232 interface
with mine, it's just a level shifter). All I need to find now is a CE124
cassette interface (I suspect that's little more than a level shifter too...)