So before people start saying "OMG! Memory-to-Memory architectures are so slow! What a stupid idea!" allow me to remind people that back in the early 70s when the 960 was turning into the 990, external bipolar memory was faster than on-chip NMOS static RAM. And since the 960 and 990 were originally implemented with a weird collection of ASICs, discrete parts and 7400-series logic chips, the idea that you would just drop a bipolar part in the design wasn't that weird of an idea. But then as the 990 evolved and TI built a single chip implementation, they retained the memory-to-memory architecture for software compatibility reasons. So yeah... ultimately... CMOS logic got faster than bipolar memory and in retrospect it wasn't the greatest design. But at the time it wasn't THAT bad of an idea. And yeah, it did make task switching very fast. But don't get me started on serial IO off the CPU. And dang, what a great, largely orthogonal instruction set. I sometimes fire up the Assembler / Editor on my 99/4 emulator just to play with it.
Anywho... this isn't a critique of the OP or @phire, it's a reminder for the community at large that tech decisions that seem bad in retrospect often had non-idiotic motivations at the time.
Anywho... this isn't a critique of the OP or @phire, it's a reminder for the community at large that tech decisions that seem bad in retrospect often had non-idiotic motivations at the time.