I am surprised at how many sub-contractors Sinclair used for his products. He had quite a media profile at the time and one imagined that everything came out o

I am surprised at how many sub-contractors Sinclair used for his products. He had quite a media profile at the time and one imagined that everything came out of a Sinclair building with all the magic happening inside that building, with Sir Clive very much hands on with his minions. In reality though the product was as much about managing suppliers and contractors as much as it was about design. The thing is that I would have thought that in those days writing your own ROM (all 8Kb of it) was core functionality and not something outsourced. Sinclair wasn't as 'vertically integrated' as I imagined. Does anyone know if they outsourced the ULA design and even the printed circuit board layout?