|Re: dbl xmem module...|
Message #2 Posted by Andrés C. Rodríguez on 19 Apr 2000, 8:08 p.m.,
in response to message #1 by Andreas Terzis
The HP 41 instruction set may be enhanced with the X Functions module, which adds functions that allow for alpha string manipulation; conversion between numeric values and alpha characters (and viceversa); programmable keyboard assignments; programmable size command; flags management; block register moves; and others.
The X functions module also introduced the concept of extended memory: registers that are not addressable by STO or RCL, or usable for running programs. Such extended memory works more or less as a solid-state floppy disk, in which you could save and later recall programs or data files. There were special functions to check the extended memory directory, to create or delete files, to access data records and to load or save programs. Although logically separated from main memory, extended memory will not survive a MEMORY LOST situation (I think it should survive, or at least ask the user what to do).
The X Functions module contains the ROM to support such functions, and also 127 registers for extended memory. There also are extended memory modules, which have no ROM but hold 238 extra registers, so the maximum extended memory was 603 registers (one X Functions and two X Memory modules). When using two "regular" extended memory modules, they could not be installed on ports combinations (1 and 3) or (2 and 4). The extended memory modules are useless without the X Functions module.
From your description, it seems that you have a non-standard double extended memory module, which may hold 476 registers.
The HP 41CX included the extended funtions on the basic machine, so the X Functions module is not needed for the 41CX. As you have a 41CV, both the X Functions module and the "double"(?) X Memory module will be useful for you. You can browse the names of the functions using a CATALOG 2 command, but you will need the Extended Functions/Memory manual to understand them. (I think it is available on this Museum CD set).
Many of the string and file manipulation functions are useful when you connect your HP41 to HP-IL devices.
Some extended functions were also incorporated to the HP42S instruction set, but not the extended memory architecture.
Hope it helps.