The first microcontroller I became fascinated with was the 8048 (and 8748). This site has a lot of info on the 8048, including an 8048 Development System.
|From Hyper Embedded - Microcontroller ASIC and EDA|
8048 The One who started it all ….
The roadside attraction of this site is the Z-80 Homebrew Computer. This was a project that I started in 1980. I moved many, many times between 1983 and 1996, and the project often was shut up in a trunk. In some cases I lost (or gave away) most of my equipment and parts. I finally got the full homebrew computer working twelve years later on several breadboards, and soldered it all up in 1993. It took me another ten years to document the system. It has been a fun ride.