alum

Alum is a file transfer tool for HP's RPL calculators.

Why Alum?

Alum (pronounced like the first part of "aluminum") is a command-line application for transferring files to and from your calculator.

Alum is intended as a replacement for software like the HP Connectivity Kit. Alum is better because:

• It is cross-platform, currently tested on Windows and Linux
• It is programmed in Rust (compiles to an executable) and requires no external dependencies, except for one small package on Linux
• Alum uses Rust implementations of XModem and Kermit, without deferring to external programs

I am retiring my previous software HPex, a GUI tool that accomplished a similar task. HPex was written in Python 3 and wxPython, which meant that the end user needed hundreds of megabytes of shared libraries and executables to run HPex. Even worse, HPex wasn't exactly a great application, and had no hope of being useful on Windows because of various multi-platform limitations.

Alum is not a GUI because a) GUI programming gets in the way of good development, b) in my experience, the average HP calculator user is comfortable in the command line, and c) as mentioned above, the software dependencies for GUI libraries are big and bloated. Alum is fast, light, and small.

Features

Alum can:

• Automatically detect a serial port to use
• Transfer via Kermit and XModem, both direct and to a server
• Calculate the checksum and size of any HP 48 object

Usage

Download a binary from the Releases page and place it somewhere convenient. You may wish to add it to your PATH variable. On Linux, Alum requires libudev to be installed for serial port detection. It is in every distro's package manager and is likely pre-installed. On Windows, Alum requires no extra dependencies.

For full usage information, run Alum with no arguments. It includes its own help, and this section is just a basic usage rundown.

Alum supports sending and receiving files to and from 128-byte XRECV and XSEND, as well as full XModem server send and receive functionality. The XModem server is integrated into the HP 49 series, accessible via [right-shift][right arrow], and is available as a library for the HP 48 series at https://www.hpcalc.org/details/5412.

Alum also supports sending files only (no receive) to the HP 48 Kermit server.

CLI

Alum uses a "subcommand" structure. The commands are:

• xsend: send file with XModem
• xget: get file with XModem
• ksend: send file with Kermit
• kget: get file with Kermit
• info: calculate file size and HP checksum on file

Each subcommand takes a file argument and optionally flags. Alum contains help for each command---simply run the command with no arguments (alum xsend) to get help.

XModem transfers

By default, the xsend and xget commands transfer to and from the XModem server. To communicate with XSEND and XRECV, specify the -d (direct) flag, as in alum xsend -d Arkalite.lib.

For example, say we want to send the excellent game Arkalite to the XModem server. That's as simple as:

$ alum xsend Arkalite.lib
Sending "Arkalite.lib" to XModem server...
################################################################################################  7/7  packets (100%)
Done!
File info:
  ROM Revision: X, Object CRC: #44ABh, Object length (bytes): 1776.0

In this example, Alum found the one physical serial port on the system and used it automatically.

Sometimes, after a file has been transferred to the calculator, the rightmost "data transfer" annunciator will stay on while the XModem server is still running. I don't know why this happens, and it appears to be harmless.

Kermit transfers

The ksend command sends files to a Kermit server or RECV command on the calculator. To use RECV, run the calculator command before you run Alum.

The kget command receives files from either a SEND command or the ARCHIVE command, if it given an :IO:<name> argument. kget does not talk to a Kermit server, to maintain compatibility with ARCHIVE. To use kget, run Alum (alum kget ARCH, the filename is used as the output name on the computer) and then start the transfer on the calculator.

Extra transfer features

To finish or close any server after a transfer, pass the -f flag to Alum, like this: alum -f ksend Arkalite.lib. If the file transfer is successful, Alum will send a quit command to the calculator after the transfer.

Limitations

Alum has only been tested with an HP 48GX. In addition, Alum will not calculate the checksum of an HP 49 object, because I have found that the algorithm I use for HP 48 objects doesn't work for HP 49 objects. Alum also does not currently support the 1K CRC direct XRECV and XSEND added in the HP 49.

Alum also does not currently support receiving files over Kermit. I'm working on it.

Future features

sorted by urgency:

• HP 49 object info
• 1K CRC direct XModem
• XModem server and Kermit server file listing (maybe)

XModem caveat

XModem is an old standard, and is so simple as to be self-destructive. The implementation used by the HP 48 pads the final packet with null bytes (0x00), and Alum trims these from the received file. However, some files have necessary 0x00 bytes at their end, and sending these files via XModem causes the object to become corrupted. For example, one file that suffers from this is the tool FIXIT, by Joe Horn and Mika Heiskanen. Conn4x suffers from this issue as well, including with this particular file. It is a limitation of the XModem protocol. If you have sensitive files, or cannot get checksums to match, send them via Kermit.

Contribute

I have documented the XModem server protocol and some HP 48 Kermit information on the Alum wiki. Feel free to edit or add to the wiki if you have information about any aspect of RPL calculator communication you'd like to share.

If you have any problems or feature requests for Alum, open an issue here on GitHub or contact me at Liam Hays on the HP Forums.

If you'd like to work on Alum, simply install Rust from rustup.rs, then clone the repository and use cargo to build. Note that cargo doesn't like if you try to use cargo run with global flags (like cargo run -f xsend Arkalite.lib), so you may have to use cargo build and run Alum directly from target/debug/alum.

Finally, if you like Alum and have an HP Meta Kernel calculator---a 48gII, a 49G, a 49g+, or a 50g---and do not need it anymore, please consider donating it to me so I can improve Alum for the Meta Kernel series. Message me on the HP Forums if you are interested.