HP50G SD card STO and RCL

[DavidM]

(11-01-2014 03:18 PM)Paul 6146 Wrote:  David
Then what is the purpose of the USER manual telling you that you can store a program into a directory on the sd card when you can't even access the directory in the File Manager? This generates an error. So in other words......the hp50G doesn't really make directories on the sd card. This says to me that all the programs you want to save to sd card must be saved in the root which is going to be a mess since there will be multiple programs that belong together all mixed up with other programs in one place. Not very good design!

The User Manual is correct, but you're making some assumptions about what it means that aren't correct. You appear to be making a mental connection between calculator directories and SD card directories, and that's where things are falling apart for you. They are not the same thing. The 50g can make SD directories on the SD card, but there's no connection between those and the ones you see on your calculator (other than the fact that we call them both "directories").

Let's say I have a newly-formatted SD card installed in my 50g. I want to save a Gregorian-to-Julian date conversion program I just wrote on the card, but instead of the root of the card, I want to save it into a SD subdirectory. I might do the following:

1) RCL the program object to the stack
2) Type in the following SD card file specifier: :3:"UTILS/DATETOOLS/CONVERT/GtoJ"
3) STO

The STO command will happily create a UTILS directory at the root of the card, and then DATETOOLS and CONVERT subdirectories beneath it. Finally, the program is stored into an SD file named "GtoJ" in the CONVERT subdirectory. This (hopefully) is perfectly understandable.

Now consider the same situation, but instead of saving a single program, you recall a calculator directory object containing multiple programs to the stack. Everything that happened above for the single program will still apply to this new scenario. Just like in the first case, the STO command will happily create the UTILS/DATETOOLS/CONVERT/ directory structure on the SD card, then save the object you gave it into a single file named "GtoJ". The STO command doesn't treat the directory object any differently than any other object -- it simply saves it as a file in the location you specified.

As a convenience, the Filer (and several third-party utilities) will show you what type of object the SD card file is, but none that I am aware of will allow you to browse the contents of that object if it happens to be a composite (list, array, program, library, etc.).