The Flite 8086 Training System: An Introduction

"Flite-86 training package eases pain of moving from 8 to 16 bit based systems"

The world's first microprocessor was the Intel 4004 way back in 1971. In 1972 Intel produced the 8008 (the first 8bit microprocessor). Unfortunately it needed at least 20 additional devices to produce a functional CPU. Two years later in 1974 Intel produced the 8080 microprocessor; it had a much larger instruction set and only required two additional devices to produce a fully functional CPU. It was also the first time NMOS technology was used and the device became the first (serious) general purpose microprocessor.

This was soon superseded by the 8085. Around the same time the Motorola (MOS) 6502 and MC6800 8bit processors appeared On the market. In 1978, Intel produced the 8086/88 16bit microprocessors which Motorola soon followed up with the MC6800.

The 8088 was chosen as the microprocessor for the IBMXT model personal computer. The rest, as they say, is history!

The 8086 is a true 16bit machine which means that the ALU (Arithmetic Logic Unit) is designed to work with 16bit numbers and the data bus is also 16bits wide, because the 8088 is hybrid in that the ALU is 16bits but the data bus is 8bits. In almost every other respect the two processors are identical. It is possible to address 1Mbyte of memory with the 20bit address bus. Both devices have time multiplexed address and data buses and some of the control pins have more than one function depending upon whether the device is operated in the min or max mode. The min mode is designed for small single processor systems whilst in the max mode the device is designed to work in medium or large systems using more than one processor.  

Incidentally, the 8086 is some 7x to 10x more powerful than the 8080. To speed up execution time, instructions are pre-fetched or pipelined into the microprocessor thereby almost eliminating instruction fetch time. This has been achieved by incorporating two separate processing units inside the 8086. The bus Interface Unit (BIU) and the Execution Unit (EU). Basically the BIU fetches   instructions and the EU executes them.

One of the problems with moving to a new processor is, having to learn a completely new set of instructions so that effective assembly language code can be written. Intel has designed its processors so that they are upwardly compatible. Code written for say, an 8085 system will also run on an 8086 system. What you can't guarantee is the reverse since the 8086 has instructions that the 8085 doesn't. But if time is tight, then upgrading to the 8086 does not pose much of a problem or those familiar with the 8080/8085/Z80 microprocessors.

Programs do not have to be written exclusively in assembly language. The processor is designed to provide direct hardware support for programs written in high level languages such as C.

There is now a widespread requirement for 16bit devices to be made available for student use. In the BTEC HNC unit 'Microcomputer Systems H', for example, it specifies the comparison between suitable 8 and 16bit devices. Obviously this can only be achieved if a 16bit device is available.

Other BTEC units such as Microprocessor Based Systems  and Microprocessor Fault diagnosis, benefit greatly from the availability of 16bit systems.

Additionally, the City and Guild's RTEEB Microprocessor Fault Finding unit has been successfully taught using 8086 target boards. Interfacing techniques and digital communications can also be explored with the right equipment.

Why Choose the 8086?

• Firstly, the answer might be -- well I'm already familiar with the 8085 and Z80 8bit microprocessors and I need to learn how to use a 16bit system quickly!
• Secondly, there is a wealth of support chips designed to interlace with this processor and many of them cost less than £5.00
• Thirdly, the PC market which uses Intel based devices takes up some 60% of the total microprocessor market! The other main processor used by industry is the Motorola 68000 family of microprocessors.
• Fourthly, and perhaps most importantly, there is an excellent all round educational package available - namely the Flite 86 from Flite Electronics International Limited.

The major problem facing educators and students is finding a complete (student centered) 16bit microprocessor learning package. When upgrading to a new system it is necessary to consider not just the hardware and software cost but staff expertise and in service training. Ideally, educational establishments require packages that are versatile. Often it is necessary to justify your choice by indicating what range of courses can make use of the chosen system. If, for example the chosen system can be used over a wide range of microprocessors, then the capital expenditure can be more easily justified.

The Flite 86 system is a complete learning package. The 8086 Controller Board is designed to simplify the teaching of the 8086 CPU and some of its commonly used peripherals. It can be linked to most PC's with a simple serial line, so that code may be assembled and debugged in a supportive software environment before being down- loaded into the RAM on the board. The board itself may then be linked to other peripherals.

Once downloaded the code may be executed and examined in a system which is accessible to the user. Data may be manipulated on the board and the effects viewed on the PC. The software which handles this two way transfer is supplied with the board, in the form of a monitor program resident on the board in EPROM, and a disk containing the 'host' software for the PC.

Apart from its use, linked to a PC, the board may also be used independently, under the control of the user, either for fault finding on 8086 systems, or for control projects. For fault finding exercises a number of test routines are supplied with the monitor EPROM which enables many faults to be investigated using simple 'scope techniques'. The accessibility of components on the board means that the faults may be easily applied.

In control applications, the board is ideal for projects from the simple 'flashing LED' variety   to sophisticated, real time systems such as floppy disc controllers. The control program can be blown into the board's EPROM’s either in place of, or in addition to, the monitor program already present. The board then becomes a powerful stand alone control system. The development and testing of the software is helped enormously by using the system linked to a PC initially, and downloading development code into the RAM.

Most importantly it comes with a comprehensively written (and easy to read) Technical Reference Manual and a set of well documented and technically accurate experiment books taking one through from simple ROM/RAM testing to multiple interrupt routines, using Flite's experiment board.

To justify that initial capital expenditure the Flite-86 can be used over a wide range of courses.