Kermit Alive and Well on the Space Station

An Ominous Cow Erred writes "Spacedaily.com reports on the use of the fantastic Kermit "program" being used to communicate with devices on the international space station. While the article's author doesn't seem to have a quite perfect grasp on what Kermit is (and effuses about how Kermit is being used to help war-torn Bosnia and advance AIDS research) it brought a smile to my face to imagine the old protocol from my BBS days (which was scorned in favor of Zmodem) being used on the greatest technological achievement of humankind."

Comments

transfer protocols comma that suck

[pheared]

(which was scorned in favor of Zmodem)

With good reason. :)

IceZmodem rocked.

Re:transfer protocols comma that suck

[Tet]

Kermit's downfall was the defaults with which it shipped. People (myself included) switched to zmodem simply because by default it gave faster transfer speeds. Yes, by messing around with window sizes, you could get just similar performance out of kermit. But no one could be bothered when zmodem "just worked". To be fair, kermit had a different set of design goals, which probably influenced the default settings. But IMHO they should have shipped kermit with default settings optimized for the common case, rather than for older, slower connections. Oh, and not being fully open source really didn't help its cause, either...

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[account_deleted]

Comment removed based on user account deletion

The line of Kermits

[shura57]

After Kermit 95, there probably will be Kermit 98, followed by Kermit NT, Kermit ME, Kermit 2000, and finally Kermit XP.

But somehow, I can't imagine Kermit Longhorn as a species... :-)

Seriously, it definitely was (is?) a great program, especially when communicating between less common platforms. It saved my day more than once when I needed to transfer files between the VAX and Amiga, both quite ancient, and without ethernet hardware on Amiga. Many thanks to the creators!

Alex

That's an interesting bulk licensing scheme...

[tcopeland]

...outlined here.

Quantity Discount Unit Price
100-249 84.38% 10.00
250-499 86.72% 8.50
500-999 88.75% 7.20
1000-2499 90.63% 6.00
2500-4999 92.19% 5.00
5000-9999 93.75% 4.00
10000-19999 94.84% 3.30
20000-39999 95.23% 3.05

I wonder how many bulk orders they get these days...

Re:That's an interesting bulk licensing scheme...

[way2trivial]

this might shock the hell out of you
I work for a cendant hotel..
cendant recently put in one of four PMS systems at every hotel in the chain.

the one at my location uses linux for the terminal, and uses k95 for windows clients..
when it runs, it identifies itself as part of a 10,000 piece license to cendant.

LeechZmodem, icezmodem, superzmodem, etc

[Anonymous Coward]

Never forget the ultimate in thieving scum protocols.
LeechZmodem.
It was a mutation of the Zmodem transfer protocol that never sent an acknowledgment packet at the end of a transfer, allowing you to download an entire file, yet signal to the bulletin board system that you'd never received the complete file. End result: your file credits don't change.
I doubt NASA cares, though.

ah the memories

[KDN]

Kermit, it wasn't fast, but I swear that protocol could almost talk through mud. I used it through terminal servers, over X.25, over DECNET, over a freaking IBM 7171 converter (anyone else remember these monsters?). I even used it to stress test a Sun to DECNET comm program (keep signing on back and forth between a and b back to a back to b back to a), and then doing a kermit file transfer. Easy way to simulate 40 people using the system simultanously. But a friend of mine has me beat, IP over kermit over a satellite bounce from the south poll.

Re:ah the memories

[vidarh]

It's trivial to make a protocol reliable. You just increase the overhead A LOT by one or more of mechanisms such as ack's, checksums/hashes to verify integrity, resends, small packet sizes etc. The reason X/Y/Z modem got popular was exactly because they threw a lot of the overhead out, increased packet sizes etc. because for almost all uses it won't buy you anything.

But getting that level of reliability is dead simple - I wrote a custom protocol implementation for data transfer between two GSM handsets many years ago that had to cope with nastyness such as frequently dropped calls (due to one of the handsets being on a ship that was continuously circling over an autonomous submersible, and the other handset being on another ship, both of them well off shore :) ), and small packet sizes and predictive resends (packages would be resent automatically if it didn't get an ack or nack within a reasonable amount of time was all that was needed to make it "rock stable" (except for the delay caused by the GSM phones reconnecting).

Serial protocols aren't exactly hard to do unless you "need" to squeeze every last byte out of the theoretical maximum transfer speed available.

Re:Zmodem rules.

[Krellan]

That's true. The purpose of ZMODEM is to transfer data as fast as possible, on a fairly modern system with clean phone lines, plentiful memory for buffering, and fast I/O that doesn't block. On a modern system, ZMODEM is the best character-based protocol out there (there were a few that were more advanced or had special purposes, like BiModem, but they are irrelevant now that everything now uses packet-based data and TCP/IP).

The purpose of Kermit is to be 100% compatible with pretty much every piece of technology, going all the way back to the earliest mainframe computers!

Different character set (ASCII, EBCDIC, UTF-8, etc.)? Kermit will translate the data as it is transferred.

Strange record length requirement (data must be transferred in units of 80 bytes or so, and can't be addressed as individual characters)? This was common on mainframes. Kermit will pad data as required to make this work.

Limited I/O that can't use the comm port and storage device at the same time? This was common on old DOS PC comm programs that could not multitask. Kermit will delay as needed in order to let data be stored before continuing with the communications, and synchronize this with the other side so that data is not lost.

Noisy phone line? Kermit will do complete error correction, without stalling or aborting the transfer (as ZMODEM was known to do).

Low memory for buffering? Kermit will do handshaking to ensure that the other side doesn't send data until the current data has been fully processed, minimizing the need for memory to buffer data.

Alien directory structure (VAX, etc.)? Kermit includes a mini-OS that can be used interactively to browse directories and initiate file transfers, and it abstracts the local storage conventions of the system's OS into a simple hierarchy that is the lowest common denominator. As an example of what this means, have you ever done a "ftp" into an old DOS system, and found yourself unable to change drive letters, because FTP (being a UNIX-based program) has no concept of drive letters? Kermit to the rescue here.

Now that computers and protocols are beginning to become standardized, thanks in part to the popularity of the Internet, the need for Kermit is fading. Still, it's good to read about interesting uses of Kermit such as this. Kermit joins the old DOS shareware program "Compushow" as having The Right Stuff.... :)

GPL/ OS licence bashing?

[pete0t2]

I'm surprised nobody has mentioned the site's long rant against open source licensing.

eg. "The very foundation of the free software movement no longer exists."