In today's technology-driven society, microprocessors and microcomputers are an integral part of peoples' lives. The applications of microprocessors are almost endless. Because of microprocessor technology, just about any electronics or electromechanical device is a candidate for automatic control. We wake up to a microprocessor-controlled alarm clock, read a newspaper that was edited by a microprocessor-based word processor, and watch the morning news on television as a microprocessor fine-tunes the picture (Goody 1993). One of the most common uses for microprocessors is in personal computers.
An ever-increasing demand for microprocessors in industrial, educational, and business organizations mandates that all students in the field of electronics be provided with a basic knowledge of microprocessor technology and its applications. The rapid advancement of computers into our everyday affairs has created society's need for individuals who are able to understand the fundamental concepts and applications of microprocessors. In order to provide electronics students with an opportunity to develop an understanding of microprocessors, this project has been included in the senior-level course, Computer Electronics - EET 445. In this course, students build an 8088-based single board microcontroller as a major project. Using Fuller's Build Your Own Computer Lab Manual, students first construct and test the basic circuit for the 8088 controller. Then, additional components are added to improve the microcomputer's functionality and to provide students with practical experience in interfacing techniques.
We selected the Intel 8088 microprocessor because it has relatively higher execution speed, larger memory size, and additional instructions, which provides students with a practical knowledge of microcontroller technology. The IBM personal computer, which came out in mid-1981, was one of the earliest microcomputers to utilize a 16-bit microprocessor, the 8088, as its central processing unit (Triebel & Singh 1997). Through the construction process, students gain knowledge and experience in circuit design, wire-wrapping and soldering techniques, board design and parts layout, static and dynamic testing, programming, use of test equipment for analysis and troubleshooting, and data acquisition. Upon completion of the project, the student will have constructed a fully functional single board microcomputer with a 64K memory, a printer port, two serial ports, an analog-to-digital converter, and over 28 parallel input/output (I/O) lines. The project is organized around the following 12 steps:
The primary serial I/O port is installed and tested in this section of the project. Serial communication in microcomputer circuits is discussed. This computer uses the 8251A Universal Synchronous/Asynchronous Receiver-Transmitter (USART) to handle serial communication. The 8251A is essentially a parallel-to-serial/serial-to-parallel converter that can be in either asynchronous or synchronous environments. It is programmable to fit a wide range of related applications (Goody, 1993). The USART is connected to the data bus where it takes an 8-bit data word and transmits it one bit at a time over a single wire at a predetermined clock speed called a baud rate. It receives data over a single wire, converting it back into 8-bit words for transmission over the data bus. The 8251A interface is interrupt driven so that the 8251A and the 8088 only talk when there is actual data to be transmitted or received. First, the circuit is wired and tested electrically. The MONITOR program is then loaded into the EEPROM and the computer is connected to a personal computer via serial ports for testing. The microcomputer is switched on and some characters are typed on the PC keyboard. If the keys are echoed by the microcomputer, the program and the circuit are operating properly. Figure 7 displays the serial I/O circuit.
Build your own 8088 Microprocessor kit 8088 Microprocessor KitWichit Sirichote, email@example.comBuild your own Microprocessor training kit with the 80C88 CMOS Microprocessor.Simple design single board computer using the 80C88 16-bit microprocessor. The CPU is Harris 80C88 40-pin ceramic package.
The original IBM PC is the most influential microcomputer to use the 8088. It has a clock frequency of 4.77 MHz (4/3 the NTSC colorburst frequency). Some of IBM's engineers and other employees wanted to use the IBM 801 processor, some preferred the new Motorola 68000,[e] and others argued for a small and simple microprocessor, such as the MOS Technology 6502 or Zilog Z80, which are in earlier personal computers. However, IBM already had a history of using Intel chips in its products and had also acquired the rights to manufacture the 8086 family.[f]
IBM chose the 8088 over the 8086 because Intel offered a better price for the former and could supply more units. Another factor was that the 8088 allowed the computer to be based on a modified 8085 design, as it could easily interface with most nMOS chips with 8-bit databuses. These were mature, and therefore economical, components. This included ICs originally intended for support and peripheral functions around the 8085 and similar processors (not exclusively Intel's), which were already well known by many engineers, further reducing cost.[g] 2b1af7f3a8