After booting uclinux, which refers to "how to use dev board",
Use tftp to transfer hello to jupiter board.
=====================================================
/bin> tftp 192.168.10.2

tftp> binary
tftp> get hello
Received 17976 bytes in 0.1 seconds
tftp> q
/bin>chmod 755 hello
/bin> ls -l
-rwxr--r--  1 0        0           47348  Dec 15 2002  arp
-rwxr--r--  1 0        0           66100  Apr 22 2003  boa
-rwxr--r--  1 0        0           14968  Dec 25 2002  cli
-rwxr-xr-x  1 0        0           17976  Jan  1 00:40 hello
-rwxr--r--  1 0        0           48252  Dec 15 2002  ifconfig
-rwxr--r--  1 0        0           24524  Apr 22 2003  inetd
-rwxr--r--  1 0        0          122224  Apr  4 2003  iptables
-rwxr--r--  1 0        0           35464  Feb  5 2003  mkfs.jffs
-rwxr--r--  1 0        0           42304  Dec 27 2002  ping
-rwxr--r--  1 0        0           49904  Dec 15 2002  route
-rwxr--r--  1 0        0           55252  Dec 14 2002  sash
-rwxr--r--  1 0        0           14776  Dec 27 2002  serv
lrwxrwxrwx  1 0        0               4  Mar  8 2003  sh -> sash
-rwxr--r--  1 0        0           13844  Dec 18 2002  sig
-rwxr--r--  1 0        0           91320  Apr 22 2003  telnet
-rwxr--r--  1 0        0           34928  Apr 22 2003  telnetd
-rwxr--r--  1 0        0           36600  Feb 14 2003  tftp
-rwxr--r--  1 0        0           38124  Apr  3 2003  udhcpc
-rwxr--r--  1 0        0           44204  Apr 15 2003  udhcpd
/bin> hello
LED toggle! q--  exit,1-- led on, 2-- led off
Hello uClinux World!
mysh> 1
1mysh> 2
2mysh> 1
1mysh> 2
2mysh> 1
1mysh> q
q/bin>
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And you will see the led on and off. ^O^