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since 1981
HP48 programmable calculator   

HP48 / C-Kermit file transfer

St├ęphane Gourichon Paris, France 12 September 2020

Prepare hardware

Gather hardware

Ensure PC recognizes hardware

We assume here that the PC side operating system runs Linux.

Prepare software

Information: why the software choice below

Get C-Kermit source my-tt and build it

Perform transfer

Run software, set HP48-specific parameters

Since Kermit protocol is very general and this implementation supports many use cases, software needs some parameters to work in our case. The lines below worked for me, words after the semicolons are comments for the curious.

./wermit ; Start C-Kermit ; The following commands are entered at the "C-Kermit>" prompt... set port /dev/ttyUSB0 set speed 9600 ; Serial port speed, HP48 defaults to 9600, also supports 4800 2400 1200 set carrier-watch off ; It's not a modem connection so ignore carrier signal state. set modem type none ; No modem is involved; don't send AT commands. set flow none ; Flow control is not supported by HP48. set parity none ; 8 data bits, no parity set control prefix all ; HP48 Kermit requires all control characters to be encoded in printable form. set file type binary ; Might not always be needed.*
* Safe default IMHO because it avoids the transfer program to corrupt the transferred data believing we expect it to change line feed characters and the like.

Note that it is not necessary to type all these commands every time you want to set up a file-transfer connection with the HP48. You can copy the commands into a file (e.g. "hp48.ksc") and then tell C-Kermit to "take hp48.ksc". Or you can define a macro in your ~/.kermrc file.

Transfer files

From that on, it's up to your knowledge of the Kermit protocol.

For example to send from PC to HP48, on the HP48 start a kermit server (menu or SERVER command), and at the C-Kermit> prompt type:

send myfilename

Or to send from HP48 to PC, on PC type


and on the HP48 put a file name on the stack (with VAR and possibly NXT, find your object in the menu, press ' and the A-F key showing the object) and issue SEND command.

Tested, success

Tested today on a PC running Xubuntu 20.04.

Both worked!


Last update: Mon Nov 30 13:09:45 2020 Validate ]