MicroProcessors and its Applications

Topics: Microprocessor, Intel 8080, X86 Pages: 18 (4089 words) Published: September 25, 2014

Descriptive Answers (in detail)

1. Explain the Evolution of Microprocessors.
Microprocessor :
Microprocessor is a multipurpose, programmable, clock-driven, register based electronic device that reads binary instructions from a storage device called memory, accepts binary data as input and processes data according to those instructions, and provides as output. A common way of categorizing microprocessors is by the number of bits that their ALU can work time. In other words. a microprocessor with a 4. bit will be referred to as a 4-bit microprocessor, regardless of the number of address lines or the number of data bus lines that it has. Intel 4004 :

The first commercially available microprocessor was the Intel 4004. produced in 1971. It contained 2300 PMOS transistors. The 4004~was a 4 bit device intended to be used with some other devices in making a calculator. Some logic designers, however saw that this device could be used to replace PC boards full of combinational and sequential logic devices. Also the ability to change the function of a system by just changing the programming. rather than redesigning the hardware. is very appealing. Intel 8008 :

In 1972 Intel came out with the 8008. which was capable of working with 8-bit words. The 8008,however required 20 or more additional devices to form a func­tional CPU. Intel 8080 :
In 1974 Intel announced the 8080. which had a much larger instruction set than the 8008 and required only two additional devices to form a functional CPU. Also. the 8080 used NMOS transistors. so it operated much faster than the 8008. The 8080 is referred to as a second-generation microprocessor. It reqires +12 V power supply. Motorola MC6800

Soon after Intel produced the 8080. Motorola came out with the MC6800. another 8-bit general-purpose CPU. The 6800 had the advantage that it required only a +5-V supply rather than the -5-V. +5-V. and + 12­V supplies required by the 8080.

For several years the 8080 and the 6800 were the top-selling 8-bit micropro­cessors. Some of their competitors were the MOS Tech­nology 6502. used as the CPU in the Apple II microcom­puter. and. the Zilog Z80. used as the CPU in the Radio Shack TRS~O microcomputer.

Three major directions of microprocessor Evolutions are
(i) Dedicated or Embedded Controllers
(ii) Bit Slice Processors
(iii) General purpose CPUs
(i) Dedicated or Embedded Controllers:
One direction has been dedicated or embedded controllers. These devices are used to control "smart" machines. such as microwave ovens. clothes washers. sewing ma­chines. auto ignition systems. and metal lathes. Texas Instruments has produced millions of their TMS-1000 family of 4-bit microprocessors for this type of applica­tion. In 1976 Intel introduced the 8048. which contains an 8-bit CPU. RAM. ROM. and some I/O ports all in one 40-pin package. Other manufacturers have followed with similar products. These devices are often referred to as microcontrollers. Some currently available devices in this category-the Intel 8051 and the Motorola MC6801. A more recently introduced single­ chip microcontroller. the Intel 8096. contains a 16-bit CPU. ROM. RAM. a UART. ports. timers. and a 10-bit analog-to-digital converter.

(ii) Bit Slice processors:
A second direction of microprocessor evolution has been bit-slice processors. For some applications. general­ purpose CPUs such as the 8080 and 6800 are not fast enough or do not have suitable instruction sets. For these applications. several manufacturers produce de­vices which can be used to build a custom CPU. An example is the Advanced Micro Devices 2900 family of devices. This family includes 4-bit ALUs. multiplexers. sequencers. and other parts needed for custom-building a CPU. The term slice comes from the fact that these parts can be connected in parallel to work with 8-bit words, 16-bit words. or 32-bit words. In other words. a designer can add as many slices as...
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