You can use a serial port mouse on your netBook in either the netBook's integrated serial port, or in the PCMCIA slot using a PCMCIA serial card. A mouse on the netBook has a much more definite, accurate feel to it than the touch screen. Bear in mind that you need a real serial port compatible mouse. In general, a ps/2 mouse with a ps/2 to serial port adapater will not work, unless the mouse specifically supports both ps/2 and serial modes. Generally, mice that support both modes come with the ps/2 to serial port adapter in the box.
CAUTION:The XTM people reported that they were able to use the onboard serial port to use a mouse in emulated windows 3.0 and their XTM machine in EPOC for a while...BUT then the mouse burned out the Psion's serial port. They were using a Series 5 or Series 5MX machine. So using a mouse on the netBook's serial port may be dangerous. A mouse would seem to draw more current than the onboard serial port can supply.
On the other hand, the netBook's serial chip is a maxim MAX3243-RS (same as on the 5MX), which explicitly supports a serial mouse. Further, there seems to be a great variation among the mice in the current that they draw, and the exact mouse the XTM people used is unknown. My ps/2 optical mouse says on the bottom that it draws 100 mA at 5V, while my trackball mouse says it draws 10 mA at 5V. So it may be possible to choose a mouse carefully for its low power requirements and use it on the netBook's serial port. Then, perhaps the XTM people were using an older Series 5 and it may be that the netBook's serial port is a more robust. The exact limits are unknown, however.
So a bit of caution is in order when attempting to use a serial mouse, at least until we get more reports back from the frontlines.
I have used a Logitech serial mouse in the netBook's onboard (/dev/ttySA0) port for sometime now without apparent harm. At the moment that is the sum total of the extent of our experience with a mouse in the onboard port.
The main issue with the onboard port is that a null modem adapter is required for the mouse to work properly. I have had success with both a handmade null modem adapter and an adapter I bought at Radio Shack. One issue is that the mouse does not always seem to be detected, or does not always seem to communicate properly with whatever program is trying to access it. I've found that booting the netBook up, after a complete powerdown, with the mouse already attached will work reliably, or disconnecting and reconnecting the serial connection - at the end of the Psion's serial cable (rather than the end of the serial mouse cable) would sometimes get the mouse working. Both of these fixes suggest that the various null modem issues may be keeping a working serial connection from forming - "ring indicator", DCD, etc... In any case, be aware that a bit of fiddling may be in order - see Troubleshooting below.
At least one PCMCIA serial card has been shown to work in supporting a mouse on the netBook. A Socket R-I/O PCMCIA serial card (ruggedized) (ebay.com, about $30) is recognized as a 16C950 serial port at ttyS0. This card is advertised as being a very low-power card (5-15 mA) so it would seem to be a good choice for the netBook. (But, no doubt there are other brands equally suitable.) This is the current the card itself draws, not neccesarily the current the card can supply to a mouse. N.B.: One needs to set
SERIAL_OPTS="baud_base 460800"in the /etc/pcmcia/serial.opts file to get linux to be able to set the correct baud rate for these particular PCMCIA serial cards.
The downside of using a mouse in the PCMCIA slot is that the slot is in use, so one cannot browse on wireless networking while using a mouse; it's one or the other. On the other hand, if you have an external modem, you can attach the modem to ttySA0 and then use your mouse in the PCMCIA slot - internet browsing with a mouse!
It is likely that the gpm daemon will operate the mouse in console mode, but this is at present untested.
If you use the XFree86 X server, you'll have to edit your /etc/X11/XF86Config file to set up your mouse type and device (/dev/ttyS0 or /dev/ttySA0). If you use the TinyX or Xfbdev X servers, all you have to do is make a link from /dev/mouse to /dev/ttyS0 or /dev/ttySA0. These latter servers will automatically probe for a mouse at /dev/mouse and determine what type it is (use the -2bottons option to obtain 3 button emulation).
Once your X configuration is set up properly, plug your serial mouse into the PCMCIA card serial port, or the onboard serial port, and start X windows. You should be able to use your mouse then. Emulate 3 buttons is supported. The mouse should be plugged in before you start X windows, of course.
The mouse that worked for me was a Logitech serial mouse, of undetermined model number.
I also used a Cirque glidepoint serial mouse that I got for $7 at the local used computer store. It's rather hard to find decent serial mice anymore! And I hate the traditional ball mouse. But, I'm not sure I like the glidepoint mouse. It's a small touch pad that operates as an ordinary serial "microsoft" mouse. In any case, you should try to find a mouse that draws a minimal amount of current to preserve your netBook's battery power. Then, some old serial mice are comparable in size to the netBook itself...
Have you verified that your mouse is indeed an honest serial mouse? Most PS/2 mice will not work, even if you have an adapter. It is hard to find real serial mice these days - try e-bay or your local used computer store. In the latter, you will likely have to sort through a dusty box of jumbled mice to find one with the serial connector.
Try plugging your serial mouse into the serial port of a desktop computer to see if you can get it to work there.
If in X windows the mouse is erratic and bounces around, then either you've set the wrong mouse protocol, or the baud rate for the PCMCIA serial card is wrong (see the hint above about "baud_base").
With your mouse plugged in, start up minicom and set the port to the correct device and the baud rate to 1200 (and 8N1, which worked for me). Then, moving the mouse should show a stream of binary characters. Nothing will happen until you get stuff coming out of your serial port.
You need to have the correct XF86Config file in /etc/X11 for the mouse to work properly. This XF86Config file worked for me.
The onboard serial port needs a null modem adapter, and as mentioned above the serial mouse can have a bit of difficulty getting a communication set up to the software. Try plugging the mouse into the serial port before you boot the linBook up, after a complete powerdown (reboot, and at the bootloader flash, do a Fn-Esc to turn the netbook off for a moment); that seems to work reliably for me anyways. Then, while in console mode (no X windows), the sequence of: (1) start minicom and check for a connection, (2) stop minicom, (3) unplug the mouse at the end of the Psion's serial cable (between the cable and the the null modem adapter) and replug it (i.e. break the connection for a moment), and (4) start minicom and check for the binary stream with mouse movement again. This sometimes seemed to work for me.
Once you see a stream of binary characters with mouse movement in minicom, the mouse should work fine when X windows is started.
It may be possible to use a USB or bluetooth PCMCIA card together with a USB or bluetooth mouse. These configurations have not been tested or tried to the best of my knowledge, however. A 16-bit USB or bluetooth card would be required, which might be difficult to find; I know nothing of bluetooth. But there are apparently self-powered, external bluetooth devices that can plug into the serial port, to obtain a bluetooth connection through the serial port. I don't think 16-bit USB PCMCIA cards even exist.