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: 
    And thinking that I had one, and sold for a cheap...some 15 years ago :(
       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 
    Time to find it :)
  3)  They are no longer supported, so they won't
program parts introduced
 in the last few years 
    I have a nice, new and USB-driven programmer (Vellon VP280) which
programs the newer chips. But sometimes I have troubles with older (BPROM
and PAL/GAL) chips. The 2900 will fit the bill.
  Data I/O and "cheap price" are rarely
mentioned together. 
    :oO I could never imagine that. Why are they so expensive? I found just
ONE (ah, a pair, ok) 2900 on ebay for - gasp - $1100 EACH. What does it has
to be so expensive? :oO