(HP71B) ASM question

[brouhaha]

(07-30-2024 07:54 AM)J-F Garnier Wrote:  I didn't know the connection to the Fairchild PPS 25.

See my comment in the HP 9199A thread, and Steve Simkin's reply.

Quote:Do you know where the Capricorn CPU architecture, used in the Series 80 and the 75C, comes from?

The HP Journal article KeithB mentioned explains their rationale for designing a custom architecture, namely BCD arithmetic and variable length data. It is unclear that any specific architecture(s) influenced it, other than the generalized influence of the BCD and variable length word of the calculator processors.

The earlier Fairchild F8 architecture (also used by Mostek 3870) was AFAIK the earliest microprocessor architecture to have 64 registers, but it doesn't really appear that it had a significant influence.