Nothing like the Xerox Alto
"I've been following Ken Shirriff's blog as he helps to get an old Xerox Alto up and working. One of the (many!) things that impressed me with this machine, was that you could add new instruction codes to the CPU on the fly.
Sounds a bit like an early FPGA to me."
No it was a microcoded arhitecture with a writeable control store. Quite common in the era of bit slice and nothing like an FPGA in architecture or in the challenge of programming it (If you consider designing an FPGA programming).
Microcode is sequential programs albeit with very wide instruction words and a direct connetcion to the hardware. a FPGA is nothing like this basically a sea of bit level connection and logic resources.
Biting the hand that feeds IT
