Not sure, but I don't think any of them are USB 3.0 capable. I know my old Garmins are a lot slower than a new Garmin. Do an internet search and you'll find big variations. The variation in non-volatile memory and SD card speeds is huge. Then there's your Garmin: it uses non-volatile memory (like an SD card), or it may use an SD card if there's not enough room in main memory.Īfter the maps download to the PC, they need to be transferred to the Garmin. Then there's the server: it may well be busy communicating with other clients, so your connection speed may be well below your maximum internet speed. And the speed with which your internet connection allows your computer to transmit to the downloading server is maybe 1/5 of the download speed. If your map file is 1.5 GB, that might theoretically take 1.5 * 1000 / 1.2 seconds, or 1250 seconds (21 minutes).īut the file is received in relatively small packets, each of which is sent with additional information that is used to detect whether it was received without errors. If you have a 12 Mbps ADSL service, you can download a stream at about 1.2 MBps (megaBYTES/second). So, our speeds are often about 1/10th of what we think they are. File sizes are expressed as bytes, and we have 8 bits/byte. That's only part of the story, and what is often forgotten is that Internet speeds are usually expressed as Mbps (megaBITS per second). People think that file size divided by Internet download speed should result in a file transfer time. ![]() I don't have a spare SD/SDHC Card to test that scenario, but that's my plan if the next Mapping update suggests the download will take 10 hours. ![]() It remains to be seen whether downloading Mapping to a PC and then using MapInstall to upload to a Nuvi or SDHC card is quicker than downloading directly to an SD/SDHC Card in the Nuvi. Download of full NA Mapping to PC was much faster than loading directly to SDHC Card in the Nuvi. Downloaded full NA mapping to my PC, including Garmin MapInstall, which can load All or selected Maps from my PC to the SD/SDHC Card and/or the Nuvi if destination space is available. (SDHC Card of course now only needed if venturing outside Canada and the Border States). Both the full NA mapping and the subset mapping (Canada and Border States) now appear in Nuvi Mapping. ![]() After updating mapping on my Nuvi 255W to "Canada and Border States", which fits in the Nuvi storage area, I reinserted my 8 GB Kingston SDHC (not SD) Card previously loaded (10.5 hours) with full NA mapping into the Nuvi.
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