I have a Tascam DR-100 and, when I put the card either into my computer's SD slot or a card reader, it shows up as "DR-100 (F:)" in Windows Explorer, "F:", of course, being the assigned drive letter. You can download a manual for the DR-1 as well as a tested SD card list, firmware upgrades and other information here:
Your digital camera may have installed a program on your computer to automatically bring up your picture files when you insert its card into the computer. To my knowledge, Tascam does not. When you insert the card from the Tascam into the card reader and connect it, you should see the drive listed under "Computer" or "MY Computer" in Windows Explorer.
I'd advise you to download the manual as well as any other pertinent goodies you might want from the website above and read them well. Tascam's products aren't the most intuitive to use and it's well to know what's what when you're trying to use them.