X-modem question

[Daniel]

Hi!
I'm developing a program using the javax.comm package. I need X-modem
support in it. And from what I understand javax.comm does not provide
this. I have googled to find any libraries to do this form me and only
find the serialio package (www.serialio.com) I have a budget to spend
on a library to solve this, so money is not a primary concern (with
some limitations of course..)
my questions are
1. Is the serialio producs good, and does the perform well?
2. are there any other libraries available that provides X-modem
support?

regards
Daniel

 

[Thomas Weidenfeller]

2. are there any other libraries available that provides X-modem
support?

There is a free software project implementing the receiving part of XModem:

http://students.washington.edu/fpotter/code.shtml

However, XModem is so simple that any experienced Java programmer should
be able to implement it within a few days.

BTW: You might want to check if you want XModem (8 Bit CRC), XModem/CRC
(16 Bit CRC) or maybe YModem (larger block size, etc.)

/Thomas

 

[Daniel]

There is a free software project implementing the receiving part of XModem:

http://students.washington.edu/fpotter/code.shtml

hehe that is just typical! I need just the sending part but oh
well..

However, XModem is so simple that any experienced Java programmer should
be able to implement it within a few days.

hmm, okay, but from looking at the price tag on serialio I see that I
have no chance of producing a (well functioning) version of x-modem to
that price. But juding from your replies it seems that serialio's
version of X-modem is okay at least?

BTW: You might want to check if you want XModem (8 Bit CRC), XModem/CRC
(16 Bit CRC) or maybe YModem (larger block size, etc.)

I want "just" x-modem (not the one called "1k x-modem" in
hyperterminal, which I assume is the 16bit crc) I must speak x-modem
as the application will transmit updated software versions to a
controllercard and it only speaks x-modem.

thanks for your quick replies!

/daniel

 

[.]

hehe that is just typical! I need just the sending part but oh
well..


hmm, okay, but from looking at the price tag on serialio I see that I
have no chance of producing a (well functioning) version of x-modem to
that price. But juding from your replies it seems that serialio's
version of X-modem is okay at least?

It has been a long time since I've used Xmodem protocol but just so you
know how simple it is, when I was a sysop on CompuServe (1983), I created
a version of XModem in BASIC 2.0 for users who did not have a good
terminal program. The program was small enough that it could be written
down and typed into your computer.

The idea was that in 1983, modems came with terminal programs with no file
transfer protocols. The XModem program was so the users could log onto
CompuServe, write down the XModem program, quit their terminal program,
type in the XModem protocol, run it and download a better terminal
program.

You might want to check out
http://www.commonsoftinc.com/Babylon_Cpp/Documentation/Res/yModem.htm

There is a section in there on XModem and XModem/CRC.

I want "just" x-modem (not the one called "1k x-modem" in
hyperterminal, which I assume is the 16bit crc) I must speak x-modem
as the application will transmit updated software versions to a
controllercard and it only speaks x-modem.

Actually, 1K-XModem and XModem/CRC are different. Read the article at the
link I provided above and you should be able to see the differences. It
covers all the variations of XModem as well as YModem.