Figure 2-1 8086 pin assignments. (Reprinted by permission of Intel Corporation, Copyright 1981.)

Figure 2-2 8086's internal configuration.

*For the 8086 the program counter is called the instruction pointer (IP).

In addition to serving as arithmetic registers, the BX, CX and DX registers play special addressing, counting, and I/O roles:

• BX may be used as a base register in address calculations.
• CX is used as an implied counter by certain instructions.
• DX is used to hold the I/O address during certain I/O operations.

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