I made this chart from my research. It is pretty nice for comparing different 7400 series's.
| Series | Release Era | Propagation Delay | Static Power (Per Gate) | Operating Voltage | Description |
| 74 | Mid 1960s | 10ns | 10mW | 4.5 - 5.5V | The first |
| 74H | Late 1960s | 6ns | 22mW | 4.5 - 5.5V | Apparently was hot but at the time was quite fast. H stands for high-speed. |
| 74L | Late 1960s | 33ns | 1mW | 4.5 - 5.5V | L stands for low-power. Quite obviously it is. (untill you look at CMOS) |
| 74S | Early 1970s | 3ns | 19mW | 4.5 - 5.5V | Uses Schottky clamping. Makes it faster. |
| 74LS | Mid 1970s | 9ns | 2mW | 4.5 - 5.5V | Pretty good. Was really popular and apparently still is. LS stands for low-power schottky |
| 74F | Late 1970s | 3.4ns | 4mW | 4.5 - 5.5V | Invented by fairchild semiconductors. F is short for FAST: Fairchild Advanced Schottky TTL. Or just because its fast for other manufactures! |
| 74ALS | Early 1980s | 4ns | 1mW | 4.5 - 5.5V | Pretty much the best it gets for TTL. ALS stands for Advanced Low-power Schottky. |
| 74AS | Early 1980s | 1.7ns | 8mW | 4.5 - 5.5V | The fastest true bipolar TTL family ever made. AS is for advanced Schottky. |




