It is based on the XC3S250E chip from Xilinx. This is a Spartan 3E FPGA.
I thought I would like to study the firmware for the FPGA, now that I am interested in such things, but to my consternation, the above Github repo does not seem to include the verilog for the chip. It has a bunch of Java code (maybe they only archived whatever miserable Java GUI they worked up). The Sigrok page describes it as "fully open source" but it looks to me like that source has been lost and misplaced.
This "Papilio One OLS" looks like a predecessor or close relative to the OLS.
In the machine shop world, everyone who gets a lathe seems to want to make a brass canon.
Perhaps in the FPGA world, everyone wants to make a logic analyzer.
Tom's Computer Info / [email protected]