HP 48GX Emulation in MESS

The HP 48GX now has both Kermit and XModem built-in protocols. XModem is faster but has less features (in particular, file names are not sent as part of the protocol). Note also that the I/O menu is now accessible by pressing the right shift key and then 1. MESS directly emulates the serial port with a minimal built-in client for both Kermit and XModem.

• to transfer a file from the host to the HP 48 using Kermit, use the -kermit file command-line MESS option to specify the file to download, then use the RECV command on the HP 48 side (open the I/O menu by pressing right shift and [1], then choose option [F])
• to transfer a file from the HP 48 to the host using Kermit, use the -kermit file command-line MESS option to specify the name of the new file on the host, put a variable name on the stack in the HP 48, and use the SEND command (open the I/O menu by pressing right shift and [1], then choose option [E])
• to transfer a file from the host to the HP 48 using XModem, use the -xmodem file command-line MESS option to specify the file to download, then, on the HP 48 side, enter a name not already used on the stack (for instance, enter 'ABC' by pressing keys [M], [alpha] twice, [A], [B], [C], and [ENTER]) and use the XRECV command on the HP 48 side (open the I/O menu by pressing right shift and [1], then [L] and [F])
• to transfer a file from the HP 48 to the host using XModem, use the -xmodem file command-line MESS option to specify the name of the new file on the host, put a variable name on the stack in the HP 48, and use the XSEND command (open the I/O menu by pressing right shift and [1], then [L] and [E])

Recall that downloaded files appear in the VAR menu (mapped to the [J] key) and that libraries must be attached to some port before usage. This is done as follows: push the library data on the stack, enter a port number (generally 0 which denotes the internal RAM, 1 and 2 denoting RAM extension cards in slot 1 and 2), press STO ([N] key), turn off the calculator (press right shift and the [ON] key), and back on ([ON] key). The program should be available under LIBRARY menu (right shift and [2] key).

The HP 48GX ROM has been through a set of revisions, from K (oldest) to R (most recent). The HP 48GX driver supports ROM revisions K, L, M, P, and R. Revisions N, O, and Q are either missing or were never released. By default, revision R (most recent) is used. This can be changed using the -bios command-line option, followed by a revision letter: k, l, m, p, or r.

As the HP 48SX, the HP 48GX has two extension slots that can accept one RAM or ROM card each. However, these slots have slightly different functionality:

• slot 1 accepts cards with 32 KB, 64 KB, or 128 KB; cards in slot 1 can be merged
• slot 2 accepts cards with 32 KB, 64 KB, 128 KB, 256 KB, 512 KB, 1 MB, 2 MB, or 4 MB; cards in slot 2 cannot be merged (even if 128 KB or smaller)

To run the emulator with an extension card, use either the -port1 file (for slot 1) or -port2 file (for slot 2) command-line option, or both. Any modification to the memory card is automatically saved to the given file when the emulator quits. When passing the name of an non-existing file, a new memory card with 128 KB capacity is created if in slot 1, and 4 MB if in slot 2.

Because the internal RAM is 128 KB and only cards in slot 1 can be merged (using the MERGE1 command available in the secondary LIBRARY menu, which can be accessed with left shift and [2]) the user memory can be extended up to 256 KB. The same care must be taken with merged memory on the HP 48GX as on the HP 48SX: do not remove or change a merged memory card, even when the calculator is turned off. Un-merge it before with the FREE1 command.

Memory cards in slot 1 appear in library port 1. Memory cards in slot 2 with 128 KB or less appear in library port 2. Memory cards in slot 2 with more than 128 KB appear as a collection of 128 KB library ports (2 up to 33 for 4 MB cards). Note, however, that due to an operating system bug, library port 33 seems to be unusable.