Hardwired logic

To create any electronic system, design engineers must first precisely define the function that they wish that system to perform. Only once that definition is complete, can a design team go about the business of choosing the optimum circuitry on which to implement their concept.

Years ago, that next step simply involved choosing the right families of discrete logic that could be assembled to realise a given function on a somewhat large printed circuit board.

But the advent of the microprocessor changed all that. Equipped with these new devices, engineers were then provided with the ability to develop systems that were configurable. Instead of being dedicated to just one specific task, the systems could be programmed to take on any job that the designer wished.

A decade after the introduction of the microprocessor, engineers witnessed the birth of the field programmable gate array. As a result, they were then given the opportunity to pack their own specific logic functions onto a single chip as well, adding yet more flexibility to their designs.

Since those early days, developments in the world of programmable hardware have continued unabated. Indeed, over the past few years, a host of new programmable devices have entered the market, taking the concept of programmability one stage further.

These new devices combine all the advantages of a programmable reconfigurable microprocessor and a reconfigurable field programmable gate array on a single chip. Now, it’s possible for the designer to extend the very instruction set of the processor itself while using the programmable aspects of the logic to target time-critical software routines.

Such programmable technology has elevated the status of the engineers that develop the underlying algorithms that perform the system-level functions into the new gods of electronic systems design. The implementation of their ideas – whether they are in discrete, programmable or reprogrammable logic – has become one of secondary importance.

That said, those of us old enough to remember the days of discrete logic will remember when it was quite possible to pick up a printed circuit board and determine its function simply by examining the logic on it. With the widespread use of these new programmable devices, however, there’s no chance of that anymore – it’s impossible to tell what’s really going on in a system, because all of the intellectual property is almost undoubtedly in some form of software.

That, of course, makes it a lot harder to judge whether the software boys that create the code based on the algorithms developed by the new gods of system design have really blessed us with anything substantive or whether they have simply produced some sloppy software with which to perform their tasks and let the shiny new programmable hardware take up the slack.

Dave Wilson
Editor, Electronicstalk

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