Would my Microchip PIC18F1320s count? They're 18-pin DIP packages
:-).
More seriously, I think we need to define 'computer'.
It should be user-programmable (which rules out most watches and cellular
phones).
It should have alphanumeric (and not just numeric) I/O.
It should be complete, not needing a terminal or TV, or something like
that (well, you can have those, but you have to count their volume as
part of the size of the computer)
In which case, small computers from my collection include HP95LX, HP100LX
(both palmtops with an 80x88 processor), HP41 (yes, it was claimed to be
a calculator, but it has the features mentioned above, the hardware
architecture is the same as just about any other microcomputer, and I
rouitinely link mine to a pen plotter, disk drive, inkjet printer, video
display, etc. Not that any of thsoe are needed to use the machine),
HP71B. Oh heck, they're all HPs...
The smallest machine I have with a CRT display is probably the HP9816
(even if you include the volume of the 9122 disk drive it boots from).
That is one beautiful small 68000 machine.
-tony