May be of interest to people wanting to program CPLD or FPGA devices: Jason Flynn has designed and expects to sell a tiny board to drive JTAG over USB.
See http://stardot.org.uk/forums/viewtopic. ... 06#p100206
[Parallel ports were the old way to do this, but they are more rarely seen these days. USB-Parallel adapters are not suitable for bit-banging.]
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In fact this FTDI FT220X chip is very capable - no crystal needed and it can produce a clock out at various frequencies, as well as drive SPI, be a UART or offer a few bidirectional I/O pins. It even includes a 3V3 regulator and can provide 50mA for external devices. It's 5V tolerant and TTL compatible. Costs under £2, but is of course surface mount.
Datasheet:
http://www.ftdichip.com/Support/Documen ... FT220X.pdf
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