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Which calculators run RPL under the hood?
12-09-2019, 07:14 PM
Post: #22
RE: Which calculators run RPL under the hood?
(12-09-2019 02:18 AM)Christoph Giesselink Wrote:  
(12-08-2019 07:24 PM)Jonathan Busby Wrote:  Are you sure? I don't remember if the 1LF2 even had a PC=A instruction.

Source Horn Disk 4 file SASM.DOC from the HPTOOLS package:

page 15:
6.  Saturn Assembler Format and Mnemonics

This chapter describes the Saturn assembler instruction set.
The Saturn CPU has three variations used in several
products.  The 1LF2 was used in the first versions of the
HP-71B.  The 1LK7 is a variation of the 1LF2 used in later
versions of the HP-71B, the HP-18C, and the HP-28C.  The
1LR2 is an integrated CPU/ROM/RAM/Display Driver IC.  Each
new version of the Saturn CPU added new instructions to the
Saturn instruction set.  Instructions available in all
Saturn CPUs are referred to as "level 0" instructions.
Instructions available in the 1LK7 and 1LR2 but not the 1LF2
are referred to as "level 1" instructions.  Instructions
available only in the 1LR2 are referred to as "level 2"
instructions.  In this section, "level 1" instructions are
marked with an asterisk (*), "level 2" instructions are
marked with two asterisks (**).  Instructions with no mark
are "level 0" instructions.

page 116:
PC=(A)      - Jump (Set PC) indirectly thru A field of A register
                            opcode:  808C
                            cycles:    23

This instruction causes the CPU to jump to the address
pointed to by memory at the address specified by the A field
of the A register.  In symbolic form, the operation is
PC=mem(A[A]).  This opcode is not available on the 1LF2
version of the Saturn CPU.

page 20:
PC=A       ** Direct jump; A(A) is the
              destination address.
PC=C       ** Direct jump; C(A) is the
              destination address.

Both opcodes PC=A and PC=C are marked with two asterix so they belong to the "level 2" instructions.

Thanks for the tip Smile Indeed, all the direct PC access instructions, including A=PC, PC=A, C=PC, PC=C PC=(A) and PC=(C) were apparently not implemented in the original 1LF2 Saturn CPU, according to SASM.DOC .



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RE: Which calculators run RPL under the hood? - Jonathan Busby - 12-09-2019 07:14 PM

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