You have four choices for protocols. The one you select will depend
upon the protocols supported by your ASCII host and by your particular
requirements. The following table shows the capabilities of the protocols:
|
Downloading |
Uploading |
|
Single File |
Multiple Files |
Single File |
Multiple Files |
| XMODEM |
Yes |
No |
Yes |
No |
| XMODEM1K |
Yes |
No |
Yes |
No |
| YMODEM |
Yes |
Yes |
Yes |
Yes |
| YMODEMG |
Yes |
Yes |
Yes |
Yes |
- XMODEM
- The XMODEM protocol is a single-file half-duplex protocol that
performs error checking. Data is transmitted in 128-byte packets.
Error checking, either by CRC or by checksum, occurs automatically.
The Z and I Emulator for Windows implementation of XMODEM first tries CRC. If the sender
fails to acknowledge the first three requests for CRC, XMODEM shifts
to the checksum mode.
- XMODEM1K
- The XMODEM1K protocol is the same as XMODEM, except that it
always uses CRC and has a larger packet size of 1024 bytes. Because
some hosts are not able to handle the 1024-byte packets, there is
a need for both XMODEM and XMODEM1K
- YMODEM
- The YMODEM protocol is similar to XMODEM, but it allows you
to send multiple files in a single transfer. You may use a set of
unique file names, or you may specify groups of files.
- YMODEMG
- The YMODEMG protocol is the same as YMODEM, supporting multiple
files, but it does not supply error checking. It assumes that the
data always transfers correctly, and is only for use with error-correcting
modems. For large amounts of data it can achieve much greater throughput
than YMODEM because it does not wait for packet acknowledgment.