I admit that I did everything with a Z80, except for using one. Because the TRS-80 used a Z80, Radio Shack carried a book on it, published by Howard Sams. It was next on the shelf after the TTL book, so of course I bought it and devoured it without ever touching a Z80.

My impression of the Z80 being clean and simple probably resulted from that book being so clearly written. It gave me a good enough understanding of how micro's work, that lasted until the more modern chips came out with things like pipelining. But I think that learning one of those old 8 bit chips would still be a great place to start for understanding things at a hardware level.

Dynamic memory refresh on chip was clever.