Книга: Introduction to Microprocessors and Microcontrollers

An 8-bit microprocessor – the Z80180

This microprocessor is the modern version of an old favorite called the Z80 which was developed in 1978 which was itself just an improved version of the Intel 8080. There are many similarities since some of the engineers that designed the 8080 left Intel and went to work for Zilog to build the Z80 which proved to be one of the most popular and longest living microprocessors – it is still widely used even in mobile phones.

When Zilog developed the Z80180, they were naturally anxious to hold on to their previous customers by making the new version compatible with the earlier Z80. This allows customers an easy and inexpensive way of updating their system without the high design costs of starting afresh with a completely different device.

The Z80180 can run any programs that were written for the Z80 as well as adding some new features. Technically, this is referred to as providing full backwards compatibility.

The X in Z8X180

If we were to go to a Ford dealer to buy a truck, they will offer us a whole series of them, all of which are basically the same but with a choice of engine sizes, gearboxes, seating arrangements and many other options. In this way, they can please the maximum number of customers without incurring significant redesign costs.

Microprocessors are much the same. They start with a basic design and similar versions are indicated by a slight change in the type number. So far, Zilog have produced the Z80180, Z8S180, and the Z8L180. By comparing the type numbers, we can see that they only differ in the third number or letter and by replacing this letter by X we can refer to a generalized type as the Z8X180. This use of X is in general use throughout the industry. The group of microprocessors are referred to as a family.

Despite the push from the computer industry for faster and faster microprocessors, there are many purposes for which small, slow and simple microprocessors is ideal. Billions of 4-and 8-bit microprocessors and microcontrollers are whirring away embedded inside things like microwave ovens, printers and instruments. Most of us share our homes with about fifty of these devices without being aware of their existence. They massively outnumber the well publicized high-speed computer microprocessors.

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