In classic digital electronics, the 7400-series (standard TTL) catalog includes a wide range of small-scale integration (SSI) and medium-scale integration (MSI) logic chips used to build complete digital circuits and systems. Which integration level correctly completes the statement?

Introduction / Context:
The 7400-series, often called “standard TTL” (Transistor–Transistor Logic), is a foundational family of logic integrated circuits widely used in education and industry. Understanding how these parts are categorized by integration scale helps learners select appropriate devices for counters, decoders, multiplexers, and basic glue logic.

Given Data / Assumptions:

• The statement references “SSI and ____ chips.”
• Context is standard TTL 74xx families (e.g., 7400 NAND, 74138 decoder, 7474 flip-flops).
• We are matching the correct integration level term.

Concept / Approach:
Integration scale classifies how many logic gates or functions a chip contains. SSI (small-scale integration) typically has a few gates or flip-flops per package. MSI (medium-scale integration) includes more complex functions such as multiplexers, decoders, adders, or register files. LSI and VLSI exceed these in complexity but are not the canonical pair used to describe the 7400 series’ breadth.

Step-by-Step Solution:
Identify the well-known pairing: “SSI and MSI.”Confirm examples: SSI → 7400 (quad 2-input NAND). MSI → 74181 (ALU nibble), 74138 (3-to-8 decoder).Conclude that the correct completion is MSI.

Verification / Alternative check:
Standard texts and catalogs list many 74xx devices that fall squarely into SSI and MSI categories; LSI/VLSI are typically separate CMOS or custom families, not the focus of classic TTL catalogs.

Why Other Options Are Wrong:
LSI: higher integration than typically associated with the classic TTL range described in the statement.MOS/MOSFET: refer to device technology, not integration scale in this context.None of the above: incorrect because MSI is the standard completion.

Common Pitfalls:
Confusing technology (TTL vs. CMOS) with integration scale; assuming LSI/VLSI were equally common in early 74xx learning contexts.

Final Answer:
MSI