Hello,
TSP Express has been retired and is no longer present in the current firmware release for the 2600B series.
If your present firmware is version 3.x.x something, I'd advise you to install new firmware. Version 3.4.2 is most current for units presently at any other 3.x level.
Firmware for 2600B Series
The older apps were built on java (Sun/Oracle) and very difficult to make work with any modern browser.
The latest firmware does still offer virtual front panel application, flash upgrade and TSB Embedded (terminal application).
If looking for an application similar to TSP Express for IV curves, take a look at the KickStart IVC (costed) application or check out our github for sample code.