[HP48] Kermit setup

[Hiwi]

I am using kermit data communication since years and there are still new builds from time to time and despite of c source you can download executables as well for nearly every platform.
The last build was from December 2022.

The implementation of the kermit protocol on the HP48 is not the fastest but works reliable.
If i have to transfer big libs i am using xmodem from teraTerm and a xmodem programm on the HP48.

But in daily use i like Kermit.
I am using an usb to serial adapter and an homebrew cable for the HP48.

The setup is simple, just extract the distribution zip file on your local storage.
I does not work out of the box you have to make some entries in the k95custom.ini file:
Put these lines at the end of the file

Code:


set port 4 ; serial com port on unix machines that is /dev/tty... or /dev/cuser...
set speed 9600          ; serial port speed
set carrier-watch off   ; no carrier detection, this is for modems only
set modem type direct   ; no modem direct serial line
set flow none           ; no flow control
set parity none         ; 8 data bits, no parity
set control prefix all  ; prefix all control chars, may be unprefix all adds some speed
set file type binary    ; better to ste this, since otherwise LF/CR may be a problem
set send paket-length 64 ; HP48 can only handle this small packets 
set terminal pcterm   ; optional
set terminal type tty ; optional, depends on the host

Now make pysical connection set HP48 to servermode, type K95.exe, connect with ALT-X go back to command console (ALT-X)
Transfer files with send file.xyz

The other way is to setup server, in command console type server
on HP 48 send file with lib I/O transfer...
Ralf

[EugeneNine]

C-kermit has been a standard install on any of my personal systems since owning an HP. I keep a script on my server that installs it to any time I build new.
https://slackbuilds.org/repository/15.0/...rch=kermit

The Kermit authors have a faq http://www.columbia.edu/kermit/faq-c-h48.html

x48 is the other staple https://slackbuilds.org/repository/15.0/...search=x48
I use my 48sx rom

Another project you may find interesting is https://recoil.sourceforge.net/
I submitted the request and information to get grob support added. So now you can create a grob of a graph or whatever on the hP48, copy it to your pc and view it.

Also the HP tools
https://www.hpcalc.org/details/4263
https://www.hpcalc.org/details/8971
and fonts
http://www.hpcalc.org/details/3859
http://www.hpcalc.org/details/3854

[cdmackay]

Nice!

My notes tell me that Kermit also has the advantage of CRC, unlike the XMODEM client in the 48?

[Christoph Giesselink]

(03-23-2023 06:56 PM)cdmackay Wrote:  Nice!

My notes tell me that Kermit also has the advantage of CRC, unlike the XMODEM client in the 48?

Yes the HP48 Kermit protocol support CRC with the fallback of checksum.

Recently I made some tests with Hyperterminal as Kermit Server and a HP48 as sender. The Kermit packets used the CRC for error checking. Same situation, but now Tera Term as Kermit Server. The request from the HP using CRC was denied by Tera Term and so the 6 bit checksum mode was used.

Yes, that's correct that the XSEND and XRECV commands inside the HP48 G-series only support the checksum method. But some 3rd party libraries, also my CARDUPL and CRDDWL HP48 programs are supporting XMODEM with CRC. Also the HP48 S-series calculators with it's 2MHz CPU are fast enough calculating the CRC instead of checksum without speed loss.

I just published a small article in the article section about connecting a HP48 and my experiences about speed and Terminal software.

[EugeneNine]

Kermit is available for Windows so your tera term isn't the only thing available

https://www.kermitproject.org/k95.html

[Hiwi]

Hi Christoph,
good and helpful article!
I know the buildin XRECV command but on my Revision M it does not work reliable.
I could not transfer any big libs without cancellation. It is reproducible.

In the Metakernel distribution pack there is another xmodem prg 'XRECV' included, which works without any problems.

Ralf

[EugeneNine]

The xmodem protocol itsself is not as reliable as kermit, that wasn't its goal. Kermit's goal is reliability as the expense of speed. Xmodem was designed for a different tradeoff. Ymodem, zmodem, etc that came after xmodem were all improvements leaving xmodem behind as one of the lessor reliable relatively speaking.

[Christoph Giesselink]

(03-24-2023 12:07 AM)EugeneNine Wrote:  Kermit is available for Windows so your tera term isn't the only thing available

https://www.kermitproject.org/k95.html

On the URL above I found no download link but I found

https://www.kermitproject.org/ckw10beta.html

showing:

C-Kermit 10.0 Beta.08/Windows-04, Dec 15 2022, for Windows

And I'm not satisfied. First issue is the "set send packet-length 94" setting.

A packet length of 94 is the default packet size with is supported by the HP48.

The length of a packet includes the SEQ number until the last checksum or CRC byte. So a

set send packet-length 94

should not exceed the packet length of 94 byte.

The suggested setting

set send packet-length 64

produce packets with a size of 69 byte!

The not counted 5 bytes are SEQ-No., TYPE D and the 3 CRC bytes. This is wrong!

So a

set send packet-length 89

produce a packet length of 94 bytes!

So any value greater 89 produce a packet size of 95 bytes, which it's out of specification.

Another issue, I installed "C-Kermit 10.0 Beta.08/Windows-04, Dec 15 2022, for Windows" om a 2nd PC with the same .ini settings. I'm not able to transfer the same data, I see garbage on the screen of the HP48 in Kermit sever mode after sending the first packet. I haven't investigated the send data so far. So the actual beta version isn't very stable near to useless.

[cdmackay]

(03-23-2023 11:21 PM)Christoph Giesselink Wrote:  I just published a small article in the article section about connecting a HP48 and my experiences about speed and Terminal software.

very useful note there, thank you Christoph.

[davidrg]

(03-23-2023 01:26 PM)Hiwi Wrote:  Now make pysical connection set HP48 to servermode, type K95.exe, connect with ALT-X go back to command console (ALT-X)
Transfer files with send file.xyz

Running k95g.exe will give you a slightly nicer experience - it replaced the console version (k95.exe) back in 2002. The console version is mostly still around for non-interactive use (as part of batch files, etc), or for anyone who really prefers it for whatever reason.

The current Windows version of C-Kermit also includes built-in support for the X/Y/Z-MODEM protocols which you can use via the "set protocol" command: https://kermitproject.org/k95manual/#c8proto (Jyrki Salmi of Online.fi, the original author of the X/Y/Z-MODEM code open-sourced it for the Kermit Project late last year which allowed for its return)

(03-24-2023 07:18 PM)Christoph Giesselink Wrote:  So any value greater 89 produce a packet size of 95 bytes, which it's out of specification.

Another issue, I installed "C-Kermit 10.0 Beta.08/Windows-04, Dec 15 2022, for Windows" om a 2nd PC with the same .ini settings. I'm not able to transfer the same data, I see garbage on the screen of the HP48 in Kermit sever mode after sending the first packet. I haven't investigated the send data so far. So the actual beta version isn't very stable near to useless.

Sounds like you may have found some bugs!

If you haven't already its probably worth reaching out to Frank da Cruz about the packet length issue (fdc@kermitproject.org, or ckw@kermitproject.org will reach both of us). I know he fixed some bugs reported by the Tera Term people in this space back in September but perhaps something was missed. Any Kermit protocol issues in the Windows version likely affect C-Kermit for Linux, Mac, UNIX and VMS also so if there really is an issue it would be good to get it fixed while C-Kermit 10.0 is still in beta.

If you've had a chance to investigate the send-data issue any further it would be good to hear if it turned out to be a bug in the Windows version of C-Kermit, or some serial hardware/configuration issue. This is the first I've heard of issues like this but the range of serial hardware I've got available to test with is limited and unfortunately doesn't include any HP calculators yet.