In the programmable logic market, the avaiability of parts capable of actually doing useful work has been an issue since the evolution of 2.5-volt parts.

I've fond it worthwhile to acquire a modest stock of 5-volt and 5-volt tolerant devices, some of which are available at VERY reasonable prices on eBay, though certainly not predictably.

The real issue is that one has to maintain an aging software tool set in order to ensure the useability of these old devices in the future. Until low-cost logic FET's useable with low-voltage output devices without interposing dlevel shifters that increase system cost by a large factor become available, 5-volt parts will continue to be extremely useful.

One problem, of course, is that discrete (SSI/MSI) logic is becoming scarce as well. (Try finding a 74AHCT133 or 74AC237 in DIP packaging, just for fun!) The result is that one frequently has to replace such parts with programmable logic. While CPLD's are pretty reasonably priced for what they are, the SPLD's are not so common either. Even a small CPLD is often more than what one needs, and a $2 part in place of what really should have been a $0.22 one is still not progress in the right direction. FPGA's are not that cheap, and, while they offer LOTS of logic, they all come in packages not very coducive to their application in what I do. If I were to work high-production, making all my assembled and tested boards in Asia, where one can still get work done with reasonable adherence to schedule, budget, and quality, the popular packaging would be no problem. Modern FPGA's don't lend themselves to application in products of which there will be no more than six units built.

That is why I like certain types of "evaluation" boards. My observation has been that there are essentially two types. One sort is the most basic, with the device of interest, a power management circuit, an oscillator, a PROM if appropriate and a prototype area and/or connectors for I/O's to be used in the evaluation. The other heaps lots of "peripherals" onto the board. With the latter type, one can experiment with the "peripherals" in the way that was intended by the designers, but, really, one can do little else.

Which type do you think you'd prefer if you had to use them for useful work?

RE