They work MOST of the time, but, when it's really important they work NOW ... well, you see what I mean, right?

The published limits on the Altera JTAG adapters essentially require you to attach them to the back of your notebook and apply them within 10" of that. That doesn't always work out. This means that you essentially have to program your part in one location and test the application in another. That's certainly not ideal.

The Xilinx versions even have a clock-rate adaptation feature that allows you to degrade the clock speed if you use, say, a meter-long cable. Those limitations apply even to the cables that they sell, namely the ones costing "50 quid." The whole issue of JTAG programmers probably should be addressed somewhere lacking in self-interest, i.e. NOT an IC vendor interested in persuading people that the cheap "thingie" is adequate.

Say ... weren't you going on holiday? What went wrong?

RE