Schottky Ttl 1970s Extend the Family with 74als and 74f
# Schottky TTL (early 1970s): Step 17 — Extend the Family with 74ALS and 74F
Extend the Family with 74ALS and 74F. Through the late 1970s and into the 1980s, TTL vendors refined the Schottky clamping technique further, producing 74ALS (Advanced Low-Power Schottky) and 74F (FAST, Fairchild Advanced Schottky TTL) families that pushed the speed-power product well past the original 74S/74LS pair.
## 1. The Second-Generation Schottky Families
Through the late 1970s and into the 1980s, TTL vendors refined the Schottky clamping technique further, producing 74ALS (Advanced Low-Power Schottky) and 74F (FAST, Fairchild Advanced Schottky TTL) families that pushed the speed-power product well past the original 74S/74LS pair. 74ALS achieved roughly 74LS's power level while cutting propagation delay by close to half, through a combination of smaller, higher-performance transistor geometries (a benefit of continued process scaling, not a new clamping principle) and more refined internal resistor and current-source design. 74F, developed somewhat independently by Fairchild, targeted a speed closer to 74S but with power consumption nearer 74LS, aiming to beat the original 74S/74LS tradeoff curve rather than simply pick a different point on it.
## 2. Real Diagram: Speed-Power Evolution Across TTL Generations
## 3. Still Fundamentally the Same Clamp
It is worth emphasizing that 74ALS and 74F did not introduce a new anti-saturation mechanism — they are still Schottky-clamped bipolar TTL, refined through better transistor geometry, tighter process control, and smarter internal circuit design, the same category of improvement that drove most of the gains across many logic-family generations in this era. This refinement extended Schottky TTL's commercial life by roughly a decade beyond the original 74S/74LS introduction, but it was fundamentally improving the existing idea rather than replacing it, which is part of why the family's eventual displacement, covered in the next two steps, came from a different technology (CMOS) rather than a further bipolar refinement.
## 4. Companion Diagram: Stage Sequence and Trend Summary
## Extend the Family with 74ALS and 74F's Place in the Process Lineage
This is step 17 of 20 in the Schottky TTL (early 1970s) series, covering the 74ALS and 74F second-generation refinements that extended the original Schottky clamping idea.