The memory is all internal, but as far as capability goes pretend that they are discs and that only one goes into the disc drive/reader at a time. If you want to switch V-Scanners you need to execute keypad commands which, to continue the metaphor, shut down the scanner and swap discs and reboot the scanner. So you can never scan more than one V-Scanner at a time.
Each V-Scanner has ten banks which can have one trunked system/zone (150 talkgroups in five lists of 30 each) and can have 50 conventional channels (reduced by however many trunked repeater channels you must program in). There are 11 V-Scanners so you can store 5,500 conventional channels and 110 trunked systems and 16,500 talkgroups, but at a single time you can only scan 500 channels and 10 systems and 1,500 talkgroups.
Also, if you take the plunge, remember that any programming changes you make are held only in the active memory. As soon as you load a new V-Scanner, those changes will be lost. If you want to retain them, be sure to SAVE that V-Scanner before you load the new one.
I have V-Scanners set up for metro areas I'm usually too far from to monitor but do occasionally visit; general road trip directions (north/west/south); and favorite vacation destinations. It is handy to have them all stored in the scanner, though the need for them would never be a surprise so it would be just as easy to keep them on my computer and upload them with Win96 as needed. Plus they're easier to manage on the computer, updating certain channels and such.
Jim