The Nebula is a Spectrum 48 daughterboard, designed to replace the ULA chip found in UK Spectrum motherboards (versions 2 to 6). It was designed by myself, Phil Ruston (PCB design, mostly) and Alessandro Dorigatti (logic core) between 2015-2016. Many thanks to Chris Smith for his excellent book: “The ZX Spectrum ULA – How to design a microcomputer” without which the module could not have been made.
The Nebula has been tested extensively on standard Spectrum 48 motherboard revisions 2, 3B and 6A and has been found to be stable on all.


Fuente:
http://www.retroleum.co.uk/electronics- ... nt-module/





