8086/8088 architectural advances over 8085 Which of the following was NOT a specific design improvement attributed to the 8086/8088 family when compared to the earlier 8085?

Introduction / Context:
The 8086/8088 introduced a significant internal reorganization compared to the 8085, including pipelined fetching and wider word operations. Distinguishing new features from generic CPU blocks clarifies learning about x86's historical evolution.

Given Data / Assumptions:

• 8086/8088 added a Bus Interface Unit (BIU) and an Execution Unit (EU) split to support instruction prefetch and simple pipelining.
• 8086 implemented 16-bit internal processing and (for 8086) a 16-bit external data bus; 8088 retained an 8-bit external data bus.
• An arithmetic logic unit (ALU) exists in virtually all CPUs, including 8085.

Concept / Approach:
We are to select the option that does not represent a distinctive improvement of the 8086/8088 over the 8085. While EU, BIU, and the 16-bit external bus (on 8086) were hallmark advances, the ALU is a basic CPU component present in both generations.

Step-by-Step Solution:
List innovations → EU, BIU, wider word/bus support.Recognize ALU as not unique to 8086/8088.Therefore, “Arithmetic logic unit (ALU)” is not the differentiator.

Verification / Alternative check:
Architectural block diagrams of 8085 vs. 8086 show the EU/BIU split and prefetch queue as 8086 family additions; both families have an ALU.

Why Other Options Are Wrong:

• Execution unit: new partitioning element.
• 16-bit data bus: external 16-bit bus for 8086; broader 16-bit processing.
• Bus interface unit: dedicated fetch/bus module absent in 8085.

Common Pitfalls:
Assuming “ALU” is synonymous with advanced capability; it is common to all general CPUs.

Final Answer:
Arithmetic logic unit (ALU)