Data I/O 2900 - How good is it?

arrived here yet) like the Vellom The 2900/3900/3980 are cost-reduced versions of the Unisite, which was one of the best universal programmers. The main drawbacks of these are: 1) The interface to a host computer is very slow a) transferring files using the floppy drive is slow, partially due to sector interleave issue b) serial interface is slow (9600bps) unless you use their proprietary "Hiterm" Windows software (115,200 bps). There is no way to use 115,200 bps with a normal terminal or terminal emulator, because Hiterm uses a proprietary protocol. c) fastest transfer is with parallel cable ("Xpi"), might not be available on 2900? requires their proprietary Hiterm Windows software. the programmer end hardware of the parallel interface has been reverse-engineered, so you might be able to build it yourself.

3) They are no longer supported, so they won't program parts introduced in the last few years

I wouldn't use these for programming recent parts, but they're great for programming older parts. I'm not sure how device support on the 29xx/39xx compares to Unisite, but the only old programmable devices I've found that the Unisite doesn't support are the first generation EPROMs (1702, 1702a, 5203, 5204), due to these needed rather extreme programming voltages (e.g., -40V to -50V) on many pins (not just one program pulse pin). The Unisite does support most bipolar PROMs, while most modern programmers do not. Data I/O and "cheap price" are rarely mentioned together.