File Transfer Protocols
Sax CommStudio includes robust, time-tested implementations of the XModem, YModem, and ZModem file transfer protocols.
Each protocol implementation has been proven to interoperate flawlessly with a very wide variety of systems, ranging from mobile devices to mainframe computers.
| ZModem | YModem | XModem |
About XModem
XModem is a very simple file transfer protocol, invented in 1977 by Ward Christensen. The original version of XModem, also referred to as XModem-Checksum, transmitted a file in 128 byte blocks with a one byte checksum for integrity checking.
There are two common variations of the original XModem protocol:
- XModem-CRC replaces the single byte checksum with a two byte (16-bit) Cyclic Redundancy Check, which greatly improves integrity checking.
- XModem-1K builds upon XModem-CRC by allowing block sizes of both 128 bytes and 1024 bytes. This reduces overhead and time spent waiting for acknowledgments.
YModem further extends XModem-1K by transmitting the filename and file size.