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Bootstrapping Xmodem on a TRS-80

I recently purchased a circa-1984 TRS-80 Model 4P, and am slowly but surely figuring out how to use it.

While I decide if I’m going to invest in a FreHD hard disk drive emulator, I need a way to transfer files onto TRS-80 floppy disks in some other way, and for now that means a null modem cable and a connection to another computer…but without a reliable Xmodem client, how does one reliably transfer files?

Well, I have to bootstrap it, by following this process.

Transferring the BASIC program which generates XMODEM/CMD is a bit of a pain in the butt because it has to be done over a non-error-corrected connection that stalls every time the receiving TRS-80 writes to disk.

There’s a better way, though: MEMDISK


  • Load up a DOS
  • Create a RAM disk with SYSTEM (DRIVE=2, DRIVER="MEMDISK") and answer the questions
  • Update the text of the BASIC program on the above page by updating the filespec on line 15 to read XMODEM/CMD:2
  • Transfer the file at 300 baud using the technique on that page, but sending it to XMDM2412/BAS:2
  • Run it with BASIC XMDM2412/BAS:2
  • Copy the resulting XMODEM/CMD:2 to its final location on a physical floppy disk

I don’t have any blank floppy disks yet–I’m still waiting for them to arrive–but I’ve successfully done the rest of this process and it works a treat.