You're right, they're pretty similar. The ZX Spectrum was a little personal computer, sold in Britain through the 80's. It was pretty cheap, probably the equivalent of $750-$1000 today. Certainly cheap enough for parents to buy for a bright young boy.

Since the ZX ran BASIC, programming for the spectrum and your TI-83 is pretty comparable, although your TI-83 was a bit more powerful. :)

http://en.wikipedia.org/wiki/ZX_Spectrum