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

chicken head
 n.

    [Commodore] The Commodore Business Machines logo, which strongly resembles
    a poultry part (within Commodore itself the logo was always called chicken
    lips). Rendered in ASCII as ?C=?. With the arguable exception of the Amiga
    , Commodore's machines were notoriously crocky little bitty boxes,
    albeit people have written multitasking Unix-like operating systems with
    TCP/IP networking for them. Thus, this usage may owe something to Philip K.
    Dick's novel Do Androids Dream of Electric Sheep? (the basis for the movie
    Blade Runner; the novel is now sold under that title), in which a
    ?chickenhead? is a mutant with below-average intelligence.


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

chicken head

    The Commodore Business Machines logo,
   which strongly resembles a poultry part.  Rendered in ASCII
   as "C=".

   With the arguable exception of the Amiga, Commodore's
   computers are notoriously crocky little bitty boxes (see
   also PETSCII).  Thus, this usage may owe something to Philip
   K. Dick's novel "Do Androids Dream of Electric Sheep?"  (the
   basis for the movie "Blade Runner"; the novel is now sold
   under that title), in which a "chickenhead" is a mutant with
   below-average intelligence.

   [Jargon File]

   (2006-07-12)