Re: HP-41C module order Message #8 Posted by Howard Owen on 7 Feb 2006, 12:32 p.m., in response to message #6 by Andreas Terzis
It's a complicated subject. But as Jim says, there are no conflicts with the modules you have listed there.
The HP-41C ROM address space is 64K, broken into 16 4K pages. The lower eight of these (0-7) are reserved for various OS bits. The upper 32K, pages 8-15, are mapped to the expansion ports like this:
Page Port
8-9 1
10-11 2
12-13 3
14-15 4
A module installed in a port may occupy 0, 1 or two of its pages. (Some modules take more than two, but these "page" the upper address space, and sometimes the lower.) The ones that occupy no pages are the so called "system" modules, like the time module and the X-memory module. Ordinary modules won't conflict with one another unless they have a collision in their ROM id. There are a copule of obscure modules that have this problem. I don't have a list handy, but they are rare. Conflicts come up more often with the "advanced" modules like HEPAX. This module plays extensive tricks with the calculator's memory map, and so it has special rules for coexisting with other modules.
Good references for this are the HEPAX module manual, available at TOS and "HP-41 M Code for Beginners" on the museum DVD.
Edited: 7 Feb 2006, 12:33 p.m.
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