Most of the chips are RCA, 5 are Mostek, and 2 are
marked:
A*
MI
AMI, American Microsystems
Almost all of the early HP PMOS calculator chips were fabbed by
either Mostek and AMI. They are custom for HP, so don't bother
looking in catalogs.
From first look the CPU seams to hafe a serial
architecture.
Yes. There is a two-phase clock and synchronization signal to
denote that start of a 56-clock cycle. There is a data line which
is used to transfer a 56-bit word to or from memory and peripherals
each cycle, although most cycles it is not actually used. There
is a line that the CPU uses to shift out an 8-bit instruction address
to ROM (addressing beyond 256 words is by bank-switching), and a line
that the ROM uses to send back a 10-bit instruction.
For more details, check out my web site:
http://www.brouhaha.com/~eric/hpcalc/
I've written a complete microinstruction-level simulator of the HP-45
which is available there.
Eric