Here are the ten best ideas for founding a start-up semiconductor company.
Rectifiers (International Rectifier)
Silicon transistors (Fairchild)
DTL (Signetics)
Operational Amplifiers (Analog Devices)
Semiconductor memory (Intel)
Programmable logic (Monolithic Memories)
Cloning PC chip-sets (Chips & Technologies)
CMOS programmable logic (Xilinx & Altera).
Graphics chips (NVidia)
Foundry (TSMC)

Dr Gordon "Silicon" Teale persuaded the geophysical instruments company Texas Instruments to invest in Silicon Transistors. If the Fairchild Camera & Instrument (aerial photography equipment) offshoot counts as a semiconductor startup, Texas Instruments effort should also. And Analog Devices' early op amps were not IC-based, unlike those of Fairchild and others (including my own not-very-good design at TI). Otherwise, I love your list.
Peter, thanks for your comments.
I always assumed that TI's start-up phase was when it went into geophysical instruments, but it would have been good to have got Dr Teale in there. I've always loved that story of how there was this conferecne, with everyone saying silicon transistors were some years off, then Teale gets up and says he's got some in his pocket.
All the best
David
Yes, I love that story about Dr Teale too! And, how about AMD as the second-source startup idea?
..And then there are twins, like Exar and Interdesign, started almost simultaneously to do what was later known as the ASIC? Interdesign was founded by Hans Camenzind, in a small space (now a shoe-repair shop) between two Chinese restaurants, although by the time I joined they had moved to a small building in a more typical industrial area.