By some reason I couldn't get any of the existing xmodem programs to work under my CP/M-8266 project so I decided to write my own small xmodem implementation.
I guess the main reasion for the problems is that I needed to use the standard main console device CON: for I/O, most old implementations uses a separate device, either as PUN:/RDR: or with direct access to the UART hardware.
The sources for xs and xr can be compiled by the SLR Z80ASM in the CP/M machine or cross-compiled with the "z80asm" package in Linux. I guess many other assemblers can be used as well with the source unmodified or slightly altered for that assemblers particular syntax, but those are the ones I use.
Receiving a file on the CP/M machine is as easy as XR FILENAME.EXT or with a drive letter added as XR B:FILENAME.EXT
Sending a file from the CP/M is XS FILENAME.EXT or XS B:FILENAME.EXT
Pressing CTRL-X will exit the program while running.