My road map for learning electronics included the 7400 series logic chips. I started in on electronics by following the labs in the "Art of Electronics" lab manual which includes labs with these chips. I ended up building several custom Microchip PIC and Atmel microcontroller boards before doing these particular labs. Now I am eye-balling FPGA's and getting excited to try one of those out. Should I leave the 7400 series behind or is an understanding of them considered fundamental to understanding the more modern programmable logic chips? Are some of the 7400 series still used in new (good) designs for simple stuff? Are there still particularly useful 7400 series chips that get used all the time? I guess it wouldn't take long just to do the 7400 series labs, but, I just wanted a sense of how obsolete they are since I had such a difficult time sourcing the parts. I couldn't find some and I ended up spending way more money than I thought was acceptable.
Thanks for all the answers! Every answer was helpful. I was convinced that 7400 still finds application in designs and are still useful today, however, usually not for larger logic designs where programmable logic is more appropriate. In addition, I was convinced that learning to use discrete logic ICs is a good preparatory step before starting in on programmable logic devices.