Book of Sigmarion II: Chapter 4 USB Mutation (Part 1)

Sigmarion II, just like most of its contemporary devices, was produced in an era of proprietary standards and peripherals. An undesirable consequence is poor and unsustainable hardware support. Many of these digital devices use their own special connectors, which made finding even just a connection cable a next to impossible proposition after all these years. 

Despite the striking similarities between Sigmarion II and Jornada 720, the former lacks PC card slot. The only expansion slot is for CF card. In addition to the proprietary serial port, since the Sigmarion series was made and sold exclusively within Japan by NTT DoCoMo, a special PHS (Personal Handy-phone System, an old Japanese mobile network system) port is added to attract those nerdy road warriors who would take the plunge into the first wave of mobile computing technology.

Now it's 2020, PHS is no more, and I am not living in Japan. Even though Sigmarion II is such an adorable device, it clearly loses to Jornada 720 in terms of expandability and connectivity. As my machine comes without the serial cable, how can I get it to synchronize with my PC if I really want to make it a daily driver?

Fortunately, thanks to stingraze on hpcfactor forums, I happened to see new possibilities to overcome the hardware limitations of Sigmarion II.

The first solution (http://databug2210.blogspot.com/2003/08/ntt-docomo-ii.html) is to embed a small USB key system board inside the machine and connect its pins to the pins on the PHS port.

The second solution (http://qdanotherside.web.fc2.com/docomo/sig2_usb_02/index.html) is to implant a USB port and connect it also to the pins of the builtin PHS port.

I find both solutions very intriguing. However, both are not without their tradeoffs. According to the writer of the first proposal, the operation seems to induce some kind of interference issue with the battery latch. When the latch is switched, the added USB port would stop working. As for the second solution, the ejection lever of the CF slot would be removed to leave just enough space to house the added USB connector.

So I was thinking whether there is an even better solution?

I am seriously ruminating on another possibility: There is another port right beside the serial port and it seems to be meant to be some sort of connector to mobile phone. I can't verify it now as I have yet to find any useful documentation of this device. 

But this port seems useless and removing it should make enough room (with some additional adjustment to the casing) for a USB port to be implanted there.

I don't actually want to embed a USB memory drive inside the machine for two reasons. In the first place, this permanent USB connection will consume the battery power constantly. Furthermore, I want to make the USB support more flexible, in particular allowing for both USB drive connection and USB connection to PC via ActiveSync.

Hopefully, a clear path would be open once I collect more information about the hardware details of this gorgeous handheld computer.

Update 1: According to this and this, the USB driver for NEC MobileGear II also works for Sigmarion II. Having spent a couple of hours digging through archived web pages, I finally found the USB driver for the FOMA usb port: 

https://web.archive.org/download/pc/module/peripheral/clik!usb/wince/cl_m4112.cab 

https://web.archive.org/download/pc/module/peripheral/clik!usb/wince/cl_m3112.cab

Update 2: Hmm. Why didn't I think of this before? As the FOMA port is actually a USB port, why couldn't I simply replace this connector with a regular USB one?

This FOMA port looks really just like a regular USB port, but with a "proprietary" (money-grabbing) connector...

Taking it out shouldn't be much of an issue here. Desoldering those two tiny soldered legs will do.

I will get to work on this tonight. May the force of the HPC be with me!

(To be continued ...)