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ZMODEM

en.wikipedia.org

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Re: ZMODEM

#41

Post by anexprogrammer »

ptaipale wrote: post #36
anexprogrammer wrote: post #3

> Introduced 1986; 30 years ago Now I feel old. I remember when this was new and clever. Made downloading from BBS's much nicer over XModem. At 2400 baud or whatever was current then!

Yup, the first problem with Xmodem was that it transferred sectors (as in CP/M) and thus file size was always padded with zeros to a multiple fof 128 bytes. Then came Ymodem which fixed this, and then Zmodem which was considerably faster (windowing protocol) and allowed resuming interrupted transfers and handled CRC checksums.

The resume was the clincher. You'd spent over an hour getting 3/4 the way through downloading an enormous 1M file to drop to line noise. OK, start again...

Saving 400+ for a Courier HST to go an insanely fast 12k (very rarely). They beat everything else at holding a line though.

Re: ZMODEM

#43

Post by narrator »

hilop wrote: post #28

Looking b ack at stuff like Zmodem, it's instructive to compare the computing culture then and now. Back then, everything was so cryptic . Documentation was hard to find printed books, code and config was extremely abbreviated ( sometimes for legitimate technical reasons of storage capacity). It was all very off-putting unless you put w lot of effort into research, or ran in the social circles that already had data a…

The other thing about coding back in those days is, if you got stuck, there was no stack overflow. You had to figure it out yourself or maybe ask a small grpup of people on a BBS or at a user group. Also, there was hardly any open source so things that seem trivial now like persistance or fast data structures were considerable efforts.

Re: ZMODEM

#46

Post by wvenable »

hilop wrote: post #28

Looking b ack at stuff like Zmodem, it's instructive to compare the computing culture then and now. Back then, everything was so cryptic . Documentation was hard to find printed books, code and config was extremely abbreviated ( sometimes for legitimate technical reasons of storage capacity). It was all very off-putting unless you put w lot of effort into research, or ran in the social circles that already had data a…

The most striking thing to me was there was a huge amount of free-as-in-beer software powering the entire BBS "network" and lots of helpful communities but almost nothing was open source.

Re: ZMODEM

#47

Post by stan_rogers »

robmiller wrote: post #7

I was a little kid connecting to the US gov list of 800 number BBSes and always had fun choosing Kermit as my protocol, but ZModem was much faster!

The trick was to split. ZMODEM down (or YMODEM before that) and Kermit up.

Re: ZMODEM

#48

Post by rsync »

qwertyuiop924 wrote: post #33
tyingq wrote: post #31

Earlier quoted context omitted.

I did put "open source" in quotes for that reason. At the time, it what somewhat novel to be able to get the source code at all, and even more novel that the writers would accept code from end users to put back into the product.

>At the time, it what somewhat novel to be able to get the source code at all Really? IIRC, in Jason Scott's excellent BBS documentary (you should go watch it. Like, right now. It's that good), Thom Henderson (from SEA. Remember them? I don't, because I wasn't alive. Which is why I have to rely on documentaries) said that it was expected in UNIX circles, which is where Kermit originated. Or were you on PC? I don't kn…

"... Jason Scott's excellent BBS documentary (you should go watch it. Like, right now. It's that good)"

Agreed. The BBS documentary is superb and really, really entertaining and engrossing. Especially the episode(s) on fidonet.

Re: ZMODEM

#49

Post by rsync »

stevefeinstein wrote: post #25

It's still hard to match the convenience of moving files to and from a server with RZ/SZ. If your terminal emulator supports it, it will see the trigger sequence emitted and start the modem protocol over your ssh connection and save the file. Since it runs over your current ssh connection it's perfectly secure. It's so much easier then switching to a local terminal to use scp to get or put a local file. Sure, I know…

I agree ... I forget to do this these days but in relatively modern days I used to use sz/rz all the time ... circa 2000-2004 I guess ...
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