What you are about to read is a handout and certainly not a book and therefore does not claim to be exhaustive and self-sufficient. This can be accompanied by documentation that can be easily found both in paper and digital form. For the drafting of this handout, in addition to the obvious information that can be found online, I took extensive inspiration from the Z80 Programming in Assembly language manuals and the New Z80 manual. As with all my other articles I apologize for any inaccuracies. Enjoy the reading.

The Z80 CPU was introduced to the market in early 1976 and quickly established itself as the most advanced performance microprocessor. At the time it was called the third generation processor. The Z80 exploited the software compatibility with the popular 8080. Although processors with superior arithmetic capabilities later arrived on the market, see for example 8088 (16bit internal bus, 8bit external bus), the Z80, thanks to its ecosystem, continued to carve out an excellent market share.
I remember that the Z80 family is made up of various peripheral chips:

• PIO parallel interface
• SIO serial interface
• Circuit for direct access to DMA memory
• CTC timing circuit

At the center of everything remains the Z80 CPU which uses a set of 158 instructions, including the 78 already present in the 8080. The Z80 CPU is therefore fully compatible with the software written for the 8080 but is not pin to pin compatible. This was a design decision, as maintaining pin to pin compatibility would have somewhat compromised the microprocessor design.

The Z80 has among its strong points:

• A wide repertoire of addressing modes, including relative and through index registers.
• Very powerful single instructions for processing data blocks.
• Simple and effective interrupt handling through a priority chain.
• Dynamic memory refresh signal managed directly by the CPU.

Finally we remember that the Z80 has equipped numerous home computers, among which we can mention MSX, Spectrum, Alphatronic, SHARP etc.

If you are interested you can find it here second dispensation.