| As explained in the Overview of Computers unit, registers are a very important part of CPU because:
- They have very fast access time,
- They are directly linked to the control unit and ALU,
- Hence, instructions that utilize registers for operands' storage execute faster than instructions which utilize the main memory for operand storage.
| | Registers are connected to other units in the CPU through an internal data bus.
| | Intel's processors 8086, 8088, and 80286 had 16-bit registers, while latter generations (80386, 80486, Pentium, II, III, IV) have 32-bit registers. These are called IA32 (Intel-Architecture 32) and contain numerous improvements over the older generations.
| | The new IA32 processors maintain backward compatibility with the older x86 processors (i.e. programs that utilize older x86 16-bit registers will still run on newer IA32 microprocessors).
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Next, the different x86 registers are reviewed followed by the IA32 registers.
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