NP-41 Emulator (may be)

[rprosperi]

(01-26-2016 12:45 AM)Chris Chung Wrote:  I was not sure before and thought that the ROM contains user domain key codes. I understand the 10 bit instruction codes but am lost on the user entered program codes. Hopefully after reading the Programmers Handbook I can gain the needed knowledge. For my current register memory "save" and "load", I just dump and load the memory image after entering the user programs by hand w/o understanding the instructions / data.

Most ROM memory is comprised of MCODE, similar (I believe) to that found in the 41 OS ROMs, however some ROMs (most notably the PPC ROM) do contain large amounts of FOCAL (user program code), however I'm not sure how these are stored.

In RAM (registers), FOCAL programs are stored using byte code as defined in the "Synthetic Quick Reference Card" found on pages 37-38 of the Programmer's Guide. Entire books (many) have been written on this subject, but the essence of the instruction format can be seen on the QRC.

"Synthetic Programming" refers to using unintended (by HP) byte sequences of user code, created by odd key sequences to edit/merge bytes, which form new instructions, which provide access to otherwise unavailable memory areas and functions. These will almost certainly be one of the first things MoHPC users will try on the NP-41.