Editing XMODEM (section)

===MODEM7===
'''MODEM7''', also known as '''MODEM7 batch''' or '''Batch XMODEM''', was the first known extension of the XMODEM protocol. A normal XMODEM file transfer starts with the receiver sending a single <code>NAK</code> character to the sender, which then starts sending a single <code>SOH</code> to indicate the start of the data, and then packets of data.

MODEM7 changed this behavior only slightly, by sending the filename, in [[8.3 filename]] format, before the <kbd><SOH></kbd>. Each character was sent individually and had to be echoed by the receiver as a form of error correction. For a non-aware XMODEM implementation, this data would simply be ignored while it waited for the <code>SOH</code> to arrive, so the characters would not be echoed and the implementation could fall back to conventional XMODEM. With "aware" software, the file name could be used to save the file locally. Transfers could continue with another <code><NAK></code>, each file is saved under the name being sent to the receiver.

[[Jerry Pournelle]] in 1983 described MODEM7 as "probably the most popular microcomputer communications program in existence".<ref name="pournelle198307">{{cite news | url=https://archive.org/stream/byte-magazine-1983-07-rescan/1983_07_BYTE_08-07_Videotex#page/n334/mode/2up | title=Interstellar Drives, Osborne Accessories, DEDICATE/32, and Death Valley | work=BYTE | date=July 1983 | access-date=28 August 2016 | author=Pournelle, Jerry | page=334}}</ref>