Citizen CBM-231

virtualbox serial ports:

  https://www.virtualbox.org/manual/ch03.html#serialports

printer manual:

  http://www.citizen-systems.co.jp/english/support/download/printer/document/user/data_box/CBM230UME_21E.pdf

printer driver for winblows 9X, NT, 2000, XP:

  http://www.citizen-systems.co.jp/english/support/download/printer/driver/windows/drvdown-e-old.htm

debian linux stty man page:

  https://manpages.debian.org/stretch/stty.1

... and example of esc/pos printing...
starting at line 26 of PrintESCPOSController.php in the linked bellow...

  https://www.neodynamic.com/articles/How-to-print-raw-ESC-POS-commands-from-PHP-directly-to-the-client-printer/

... and more "notes"... http://scruss.com/blog/tag/stty/