Just sharing some strange experiences on this subject:
With the assumtion that a soldered SD-card in a friend's TomTom ONE V3 would "replace" the internal 512MB, I soldered a nice, new 4GB SDHC card, with a working NavCore 8.412 and map on it.
(navcore 8.412, small map, fastactivate. All on the internal 512MB. Tested it: OK. transferred it via USB to the 4GB SDHC (wich was in my PC's cardreader))
Deleted everything on the internal 512MB, soldered the 4GB SDHC in the device with a nice, sleek, ribbon-cable, made the CD-GND-connection. (thanks to OpenTOMTOM, who have a nice
[Please Register or Login to download file] on their website)
Reseted the TomTom... Bootloader starts, but instead of the yellow progress-bar, I got a red blinking cross, indicating there is nothing to read.
How strange. The bootloader is 5.5128 so SDHC shouldnt be a problem.
After lots, resets, flashclears, CD on/off switching and cursing, I never got it booting from the just added SDHC-card.
At this point, I assumed the TomTom just didn't "see" the SDHC-card for whatever reason, also because when connecting to a PC with the USBcable it just showed the empty internal 512MB.
At last I copied the backup (only difference: older map) back to the internal 512MB and guess what...
The TomTom booted from the INTERNAL 512MB and came up with THE MAP wich was on the 4GB SDHC-card !
Although this system works, as a whole, right now, its worthless because the content of the 4GB SDHC-card cant be changed because its never accessable from the outside, unless its de-soldered, contacts made clean and put in a cardreader.
Also, I have no idea wich files it exactly uses from the internal 512MB and wich from the SDHC-card.
Also, after removing the CD(Card Detect?)-connection its still working the same way.
The drivename wich you see when you connect the TomTom to the PC is from the SDHC-card, but the content is from the internal 512MB !
If this is all normal and the way it was ment to be by TomTom, I find it strange that no sources mention that its TRIVIAL to use an MicroSD-adapter and for every map-update the device need to be opened...
RJ45