Using LEDs, LCDs and GLCDs in Microcontroller Projects

1.2 Evolution of the Microcontroller

The first microprocessor, named the 4004, was introduced by the Intel Corporation in 1971. This was a simple 4-bit device, supported by three other chips to make a computer; the 4001 and 4002 memory chips, and the 4003 shift register. 4004 was initially used in calculators and in simple control applications.

Shortly after the 4004 appeared in the commercial marketplace, many electronic companies realised the power and future prospects of microprocessors and so have heavily invested in this field. Three other general-purpose microprocessors were soon introduced: Rockwell International 4-bit PPS-4, Intel 8-bit 8008 and the National Semiconductor 16-bit IMP-16. These microprocessors were based on PMOS technology and can be classified as the first-generation devices.

In the early 1970s, we see the second-generation microprocessors in the marketplace, designed using the NMOS technology. The shift to NMOS technology resulted in higher execution speeds, as well as higher chip densities. During this time, we see 8-bit microprocessors such as the Motorola 6800, Intel 8080 and 8085, the highly popular Zilog Z80, and Motorola 6800 and 6809.

The third generation of microprocessors were based on HMOS technology, which resulted in higher speeds and, more importantly, higher chip densities. During 1978, we see the 16-bit microprocessors such as the Intel 8086, Motorola 68 000 and Zilog Z8000. The 8086 microprocessor was so successful that it was used in early ...