to Rev.4 from older versions of Sparrow LITE board
difference between Rev.4 and older versions of Sparrow LITE boards is in
another 3 signals added to the
internal system connector ZX_AUX50 - /NMI, /M1 and /RESET.
in fact you can upgrade the Sparrow LITE Prototype 2, Prototype 3 or
Rev.3 to Rev.4 by soldering three wires to board, as you see on