PDF datasheet from Texas Instruments identified only by its literature code SDLS138, about 311 KB. The name does not say which device is inside, so read the title page before relying on it. The SDLS series covers TI's classic TTL logic lines. Technicians use these documents to look up pin assignments, logic functions, recommended operating conditions and propagation delays. Before you use the pinout to trace or replace a part, check the full marking and package against the document.
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The standard format for schematics, block diagrams, power-sequence charts and service manuals.