Hi; This is probably a dumb question to which everybody knows the answer but me. I have found and received a great deal of valuable help and explanations regarding what happens between pushing the power button and a computer begins the actual boot instructions. One question remains outstanding. " ... the CPU starts processing. The very first operation performed by a CPU is to fetch an instruction from address FFFF:0000h. Since this address is almost at the end of available ROM space, the instruction is almost always a jump command (JMP) followed by the actual BIOS ROM starting address. ..." and further on; "... Next, BIOS looks for the presence of a video ROM between memory locations C000:0000h through C780:000h. In just about all systems, the search will reveal a video BIOS ROM on a video adapter board plugged into an available expansion slot. ..." In both statements, there is mention of two separate ROM addresses as opposed to the computer's RAM addresses. How does the CPU know that a particular address is ROM based, located in a different place than RAM? For example, using the above mentioned ROM addresses does, the FFFF: or the C000: signify a specific location for the ROMs? I have googled for 'address' and 'memory' and all the variations I can think of. All answers have explanations of how RAM and VM work -- which I can follow. None has an explanation of how the CPU finds ROM addresses. Any explanation or guidance would be welcome. -- Regards Bill