The X86 Microprocessors: Architecture and Programming (8086 to Pentium), 1st Edition

504 THE x86 MICROPROCESSORS

 e address bus was increased to 24 bits, which could address 2ii)

24

bytes or 16 Mbytes of

physical memory.

 e memory cycle time was reduced from 4 cycles to 2 cycles which made a direct iii)

improvement to the speed factor. Calculation of the more complex addressing modes (such

as base + index) had less clock penalty because it was performed by a special circuit.  e

8086, its predecessor, had to perform eff ective address calculation in the general ALU,

taking many cycles. Also, complex mathematical operations (such as MUL / DIV) took

fewer clock cycles compared to the 8086.

 e biggest change and enhancement, however, was in the form of the introduction of what iv)

was called the ‘Protected Virtual Addressing ...