The Jargon File (version 4.4.7, 29 Dec 2003):

bitty box
 /bit'ee boks/, n.

    1. A computer sufficiently small, primitive, or incapable as to cause a
    hacker acute claustrophobia at the thought of developing software on or for
    it. Especially used of small, obsolescent, single-tasking-only personal
    machines such as the Atari 800, Osborne, Sinclair, VIC-20, TRS-80, or IBM
    PC.

    2. [Pejorative] More generally, the opposite of ?real computer? (see Get a
    real computer!). See also mess-dos, toaster, and toy.


The Free On-line Dictionary of Computing (30 December 2018):

bitty box
calculator

    (Or "calculator") /bit'ee boks/ A computer
   sufficiently small, primitive, or incapable as to cause a
   hacker acute claustrophobia at the thought of developing
   software on or for it.  The term is especially used of small,
   obsolescent, single-tasking-only personal computers such
   as the Atari 800, Osborne, Sinclair, VIC-20, TRS-80
   or IBM PC, but the term is a general pejorative opposite of
   "real computer" (see Get a real computer!).

   See also mess-dos, toaster, toy.

   (1994-11-29)