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Ángel Martin · (This post was last modified: 09-05-2019 07:50 AM by Ángel Martin.)

(09-04-2019 09:45 PM)hth Wrote: Take a look at the COPY routine in mainframe (HP-41 firmware) and how it works. It uses the old .END. to become a new local (plain ordinary) END. Then program bytes are copied into registers. The two extra words serve two purposes, to tell how many registers are needed (for PACKING - TRY AGAIN) and to tell how many NOPs go into the first register to fill up registers evenly. No new .END. is created by the COPY code, it is the END if the RPN program in ROM that becomes the new permanent .END..

We're in agreement that the program length needs to be included in ROM as well, otherwise COPY won't work. But that's not the same as the CHAIN information, right? There's no need for a pointer to the following global LBL or END instruction in ROM, I always assumed that those were written (in RAM) by COPY as part of the action...