11. XMODEM was written for CP / M machines, and bears several marks of that operating system.12. XModem used a slightly larger 128 byte packet, which takes about of a second to send.13. File transfer options include the ZMODEM, XMODEM and YMODEM transfer protocols ( using parts of SEXYZ .) 14. XMODEM , as it was intended, there was a potential 10 second delay before the transfer started.15. LeechZmodem was a mischievous ZMODEM variant ( among similar XMODEM and YMODEM derivatives ) that cheated BBS download quotas. 16. This meant that if the user selected XMODEM -CRC while attempting to talk to " any" 17. XMODEM was designed for simplicity, without much knowledge of other file transfer protocols which were fairly rare anyway.18. XMODEM -1K was originally one of the many improvements to XMODEM introduced by Chuck Forsberg in his YMODEM protocol.19. XMODEM-1K was originally one of the many improvements to XMODEM introduced by Chuck Forsberg in his YMODEM protocol. 20. For automated transfers between two sites, a number of add-ons to the XMODEM protocol were implemented over time.