Although the real mode will run existing 8086 programs, there are limitations associated with the real mode. First, it limits the amount of physical memory which can be addressed to 1 megabyte. (In some computers, such as the IBM AT, the amount of physical memory available for programs has...
These are the 6522 versatile interface adapter, (VIA), usually associated with the memory mapped 6502 microprocessor systems and the 8255 programmable peripheral interface, (PPI), associated with such processors as the 8080, Z80 and 8086 in port addressed systems. 3.2.4.3 The 6522 VIA This is ...