|Re: Downloading ROM functions|
Message #2 Posted by Vieira, Luiz C. (Brazil) on 3 Feb 2003, 10:04 p.m.,
in response to message #1 by Steve
there is a way to generate ROM images from existing ROM modules, but it needs specific hardware (other ROM modules) that allow it to be done. These ROM modules (if I am not wrong the CCD and the PPC ROM's allow this sort of procedure) are somewhat hard to find. Even so, if you have the ROM image, I cannot figure a way out to use it internally unless you build a ROM module with that image, say, you will even need the external HW to accomodate the ROM data you have already downloaded. There is no available hardware inside the HP41CX to hold this data, and I believe the 2233 bytes will not be enough to hold all of the I/O programs. Even if you do it, there will be no room for anything else, right?
If you store the ROM image in the X-Memory there it will be necessary to find a way to use the X-Memory contents directly. I know that some synthetic maneuvers allow a program stored in X-Memory to be ran without copying it to RAM. I tried it once and it worked fine, but the XEQ instructions generated NONEXISTENT error, so I simply did not try again. But this works with programs, I do not even know how to store a ROM image in the X-Memory space.
All of this is based in some experiences of mine and some posts in here. But I am almost sure it cannot be done witn the unique HP41CX available hardware.
Hope you have other, better news.