Several years ago I wrote a GUI frontend for the Velleman k7103 PC Storage Oscilloscope.
The DSO is connected to the PC with a parallel printer cable. Most modern PCs don't have this interface any more. USB to Parallel converter cables don't work as interface because special control signals are used by k7103.
Therefore I developed a USB interface for k7103. k7103-USB is a dedicated interface with direct connection to the internal signals of the k7103. It offers all features of k7103 as available with the parallel printer cable. Additionally, an increased bandwidth for the data transfer of the sampling RAM to the PC is achieved. The K7103 frontend is extended with an appropriate driver for the new USB interface. It achieves approx. 70 acquisitions per second at my Core-i7 at 2.8GHz.
An additional PCB (100x76mm) is inserted into the k7103 case and connects to several digital chips of the k7103 PCB. k7103-USB mainly contains a Cypress AN2131Q EZ-USB 8051 microcontroller (MCU) and a Xilinx XC9572-PC84 CPLD.
Find more information on the GUI frontend and the k7103-USB hardware at