IDT Winchip C6 180
The slowest WinChip C6 released. The IDT WinChip Processor Databook mentions a 150MHz model in a table with power dissipation figures but a 150MHz CPU is nowhere to be found. I guess at one point in time it was on the horizon but never materialised. Probably a good thing since its performance would have been abysmal in 1998.
ST300A 