My first computer was a wire wrapped home brew with a Signetics 2650 cpu, and a handful of 74LS logic and 1kx4 static ram chips. The Signetics 2650 cpu had an

My first computer was a wire wrapped home brew with a Signetics 2650 cpu, and a handful of 74LS logic and 1kx4 static ram chips. The Signetics 2650 cpu had an 8 level on chip return stack. It was a good microprocessor for the time, easy to interface, and generally nice to program. But, there was no way to extend the stack or even access it so it could only be used when the call depth, including interrupts, could be guaranteed never to exceed seven levels. It enjoyed some success as an embedded cpu, but was never used in personal computers, probably because of the stack limitation.