The Museum of HP Calculators

HP Forum Archive 16

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HP-49g+ and SD card
Message #1 Posted by Antonio Maschio (Italy) on 4 Dec 2006, 12:30 p.m.

Hi,

is there a connectivity kit able to transfer data directly to the SD card?

Thanks.

-- Antonio

      
Re: HP-49g+ and SD card
Message #2 Posted by Les Wright on 4 Dec 2006, 1:29 p.m.,
in response to message #1 by Antonio Maschio (Italy)

I have an SD card reader on my computer so I never use the USB cable or the connectivity kit that comes on the CD. Just copy files directly to the SD card and find and load them by navigating thru the "Files" screen. I swap little programs back and forth between Power48 on my Palm XT and the 49G+

I guess it depends on what you are specifically asking for. If there is a way to get ones PC to recognize the HP49G+ as an SD card reader so you can just drag and drop files via windows explorer, I would be interested. I believe the provide Conn4x software just lets one access the calc's RAM, not the contents of the SD card.

Les

            
Re: HP-49g+ and SD card
Message #3 Posted by James M. Prange (Michigan) on 5 Dec 2006, 3:56 a.m.,
in response to message #2 by Les Wright

Quote:
I have an SD card reader on my computer so I never use the USB cable or the connectivity kit that comes on the CD. Just copy files directly to the SD card and find and load them by navigating thru the "Files" screen. I swap little programs back and forth between Power48 on my Palm XT and the 49G+

Yes, the SD card port amounts to a built-in mass storage drive with removable media; you could think of the SD card (or MultiMedia card) as being like a very large floppy or a CD-RW, or with the largest cards, maybe a DVD RW, although the calculator has rather limited capabilities for managing files and directories on the card.

When the calculator stores a file on the card, it amounts to a binary transfer, including an HPHP49-X transfer header before the object. If you have a card reader for your PC, then you can simply transfer a file between the card and your hard drive. When the calculator reads a file on the card (or receives any binary transfer, for that matter), it checks for a valid binary transfer header (it must begin with HPHP49-), and if it has one, it does some validity checking on the object; I don't know how much, but at least the correct length. If the file is determined to be not valid for the 49 series, then its contents are embedded within a character string object.

The calculator can execute files on the card, in which case the object is transferred to RAM before execution. But a library file on the card cannot be attached; for that the library object has to be stored in port 0, 1, or 2.

But the calculator doesn't allow for an "ASCII" transfer (object decompiled to command line editor form, optionally with character translations) with the card that makes it easy to view, edit, or write source code on the PC. For that matter, it doesn't allow for ASCII transfers when using the Xmodem protocol either. I don't know why; it would've been very easy to add these capabilities.

Anyway, I wrote my own UserRPL programs to make ASCII transfers with the card (or Xmodem or plain "serial I/O", for that matter) easier. Being UserRPL, they're fairly slow (expect a few seconds to do a translation), but they do work, and they're easy for a user to do any customization on. For these programs, see ASCII on SD.

Quote:
I guess it depends on what you are specifically asking for. If there is a way to get ones PC to recognize the HP49G+ as an SD card reader so you can just drag and drop files via windows explorer, I would be interested. I believe the provide Conn4x software just lets one access the calc's RAM, not the contents of the SD card.

That would be nice, but as designed, any transfer using USB, IrDA, or, on the 50g, the serial port, involves transferring the file to or from System RAM, although via the underlying ARM processor. This way they could reuse the routines written for previous models instead of starting from scratch. I suppose that using HPGCC, it might be possible to bypass using the emulated Saturn+ processor and System RAM and access the card as if the calculator were a USB SD card drive.

I suppose that an RPL program could be written to transfer information about the card's file system via USB, and recall or store files on the card via USB, but the file size would be limited to what can fit in the available System RAM, and it might be fairly slow.

Regards,
James


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