jmunkki@kampi.hut.fi (Juri Munkki) (03/21/90)
I'm having problems with the HP48SX kermit. I just did a total reset without first checking that my backups were ok. Now I discover that the backups are received as strings and not backup objects as they should be. I have implemented my own kermit, so I know some of the pitfalls. My own kermit does not work with the HP. This might be my fault, since MacKermit, VersaTerm Pro and MicroPhone all seem to work fine. I say they seem to work, since I have now discovered some problems. First, let me tell about the bugs that I found when I tried to make my kermit implementation work with the HP in binary mode: 1) If the 6-bit checksum is used, the HP often calculates a checksum that is incorrect. This value is quite close to the correct value (the difference is two). This happens only in binary mode with 7-bit transmission and ctrl-character prefix. 2) If the other end specifies a packet length shorter than 80 characters, the HP just ignores this and sends 80-character packets. Fortunately most kermit implementations accept this. I just tried smaller packets to make debugging easier: it didn't work! The first one is the reason why the HP kermit will not work with mine. If I modify my program so that it accept the incorrect checksum, everything is fine. I don't want to make that modification to my program. I verified the checksums by hand. My calculations agree perfectly with my program. The third problem came up when I used an 8-bit connection between VersaTerm and the HP kermit. This time "Y" characters were lost. Now this is something that is familiar to me, since I had this bug in my kermit when it was still in it's alpha-testing. The problem is that it is perfectly legal to tell the other end that the bit-8 prefix is "Y". If both ends agree, no prefixing will be done for characters with bit 8 set. When the HP interprets a "Y" as a prefix, it looses the Y and the next character. This problem affects binary and text transmission I assume that something like this is also making my backups unusable. For some reason, some short binary files transfer ok (like the inprt program and the peek and poke programs that I uuencoded). Now do I get new ROMs because of these problems? Probably not, but I wish I would. I hope I'm wrong about these bugs and that the HP kermit is ok after all. It just looks like I've found some nasty bugs. I'm getting sick of kermit. They tell me that kermit should work through anything, but all these new additions to kermit (like windowing and crc checksums) allow bugs to creep in commercial distributions. As you all know, kermit may not be sold for profit, so we have a lot of unofficial kermit implementations. XMODEM works a lot better, although it has its faults (like requiring a pure 8-bit connection). ___________________________________________________________________________ / Juri Munkki / Helsinki University of Technology / Wind / HP S / / jmunkki@hut.fi / Computing Center Macintosh Support / Surf / 48 X / ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
rayde@hpcvia.CV.HP.COM (ray_depew) (03/23/90)
(Not speaking for HP officially..... )
Sorry to hear about Juri's problems with Kermit and the HP-48SX. I've
used Kermit successfully on PC compatibles and my own (shhh!) Atari ST,
working with the 48 with no problems. The Kermits (plural?) I've used were:
PC:
ProComm version 2.4.2
KERMIT.EXE (the one on the PCLink disk)
ST:
Flash
UniTerm
Kermit
I've tried many
different options (ASCII/binary, checksums, etc.) and the protocol has
proven to be remarkably robust.
An anecdote: I was using Kermit to backup my 48 (via I/R) to a colleague's
machine. Someone else walked up and said, "OOOH, is that the new calculator?"
-- reached down -- we yelled "DON'T!!!" -- too late, he picked one up --
stood there holding it for an ETERNITY -- we snatched it out of his hands
-- put it back on the table -- after another retry, the machines succesfully
completed the transaction.
I can't speak for the Mac community, as there were no Mac cables around when
I did all this work. But you should find the HP-48SX Kermit to be equally
robust with the Mac.
Good luck.
---------------------------------------------
Ray Depew
another satisfied HP user
HP InkJet Components Operation
hpcvia.comlorner@csuchico.edu (Lance Orner) (03/24/90)
In reference to Kermit transfer with the 48s:
I've gotten it the 48 to work with my own jury-rigged cable on the Macintosh,
using White Knight software. Everything works well and good, except that
the 48 expects linefeeds after every line, but the Macintosh will usually
fight with them.
On most word processors on the Mac, all of the linefeeds will show up
as little square boxes at the beginning of each line. A program like
Microsoft Work will seem to have all of the original lines printed like a
huge run-on sentence, with little boxes separateing them, but some processors
are a little better than this. With Word, if you copy one of those little
boxes onto the clipboard, do the global change function to change the box
(which you paste into the field) to a newline characted (in this case '^n'),
the screen will be formatted correctly. Then, when you save it, save the
file as a text file _with line feeds_, then the file will transfer correctly.
I had set up my terminal program to strip out all of these linefeeds completely
when downloading automaticlly so I wouldn't have have to worry about them
later. But now, I had to turn that off, so the linefeeds will come through,
so I can change them to newline characters that don't mess up the Mac, and
then back to linefeeds on the way out.
Sort of a struggle, but you can sort of streamline the system when doing
a lot of files at once. Does this make any sence?
----Lance Orner
California St. Univ., Chico
lorner @ csuchico.edudan@Apple.COM (Dan Allen) (03/26/90)
In article <31210009@hpcvia.CV.HP.COM> rayde@hpcvia.CV.HP.COM (ray_depew) writes: >I can't speak for the Mac community, as there were no Mac cables around when >I did all this work. But you should find the HP-48SX Kermit to be equally >robust with the Mac. I have been using the Kermit software with the Mac and HP-48SX for two months now and they work great together. No problems here... Dan Allen Apple Computer