[http://en.wikipedia.org/wiki/IBM_Personal_Computer About the original IBM PC]
[https://bitsavers.org/pdf/ibm/pc/GG24-3057-00_IBM_PC_Internals_Fundamentals_Course_Notes_198603.pdf IBM PC Internals Fundamentals Course]
[https://bitsavers.org/pdf/ibm/pc/pc/6025008_PC_Technical_Reference_Aug81.pdf IBM PC Hardware Technical Reference]