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

ZX Spectrum
Spectrum

    Sinclair's first personal computer with a colour
   display.  The Spectrum used the Zilog Z80 processor like its
   predecessors the ZX-80 and ZX-81.  It was originally
   available in 16k and 48k versions using cassette tape and
   later grew to 128k and sprouted floppy disks.  It had a
   wider and more solid case and a marginally better "dead flesh"
   keyboard.  Unlike the earlier models, it didn't require the
   presence of a cold carton of milk to prevent it overheating.
   It was possibly the most popular home computer in the UK for
   many years.

   The TK-90X was a clone.

   (1995-11-04)