UPDATE! It has taken me 3 replies back from Auterra Support, but at last my Handspring Visor Prism (Palm OS 3.5) and the Auterra A-300 are working happily together. I am even using my original Handspring serial cable cradle, which Auterra did not think would work. I ended up having to download the files from their website, as it seems the files on the included CD are corrupt or something. The A-300 setup is okay, but a little cumbersome as I cannot use the buttons to make selections; I must use the stylus or my finger to make menu changes.
It does display 2 to 5 parameters of your choosing simultaneously, and even works on my CAN bus Dodge RAM. These are in digital numbers, with small bar graphs. There are also two color graphs that can be selected, but I have not tried that yet. I still need to find a way to somewhat permanently mount this thing in the truck so I can really watch what it shows me.
What I do find a little frustrating is...when I leave the DynoScan program to use any other function on my Visor, DynoScan forgets what parameters I was watching on the list and meter displays.
Here is the gizmo I actually purchased:
Palm OS Scan Tools - Automobile OBD II Scanner for Palm PDAs I suspect it may be better with the T3 I have, simply because the T3 has better screen resolution. The A-300 requires a serial cable though, and I'll need to buy one from them for any other device I use... More to come as I get better acquainted with this thing.