How did Linux get on sdc when I insalled it on sdb Are you trying to add a Linux option to your Windows Boot Manager to boot Linux off of an external hard drive? It's probably going to be much easier if you just directly boot off of the hard drive instead, pressing F12 (Dell) or similar on bootup to select a boot device.
How many memory addresses can we get with a 32-bit processor and 1gb ram? Np. Intel CPU's have two address spaces: "Memory" and "I/O". Things other than RAM appear in the "Memory" space. Other things such as I/O devices or ROM may be at spots unoccupied by RAM. Generally only I/O devices appear in the I/O address space.