The following short programs are examples of how to use a device.  Both
send the serial device command SDCMD_QUERY to the serial device to
determine the status of the serial device lines and registers.  The first
program is for pre-V36 versions of the operating system (before Release 2)
and the second is for V36 and higher.  You may use the pre-V36 version
with V36 and higher, but you may not use the V36 version with older
systems.

The programs differ in the way they create the message port and I/O
request.  The pre-V36 version uses the amiga.lib functions createport() to
create the message port and createextio() to create the i/o request; the
V36 version uses the Exec functions createmsgport() to create the message
port and createiorequest() to create the i/o request.  those are the only
differences.

     device usage example (pre-v36) 
     device usage example (kickstart v36 and up)