I'm looking over the documents for YMODEM found here.
Scroll down to page 8, the section on 1-k blocks. Note that the protocol can switch between 1024 and 128 bytes by sending an
Now scroll to page 12, the section on CRC. Note that it is also switching packet sizes, but in this case it is sending 1024 byte blocks with an
SOH header. The same oddity appears on page 14 in the section on the g-option.
Is this a bug in the documentation? Does anyone have a canonical implementation of YAM to refer to? I suspect that 1024 is a typo which was then copy-n-pasted.