Cyclone III Remote Update registers

I'm trying to understand the Remote Update on the Cyclone III. Per the code example in Quartus II Handbook Chapter 28 example 28-1:

// Perform the reconfiguration by setting bit 0 in the

// control/status register

IOWR( remote_update_base, 0x20, 0x1 );

Where does the 0x20 come from? The documentation above this example says 00-1F maps to the param and read_source bits of the hardware.

I want to read back the boot address so the factory NIOS II application running after a reconfiguration can find the NIOS II update application which follows the configuration data in the EPCS. It will then copy the update application over the factory application and restart the software (so it is now using the application reconfiguration data loaded on the reconfig).

I am having trouble reading any of the Remote Update registers at runtime, and reading registers in the debugger does not show what I expect (if I write 0x12345 to the boot address I don't see any update in the window that corresponds to this value (<< 2 of course).

I have everything working except detecting a reconfiguration. I want to know if I should be running the update application, not the factory one. I know the common solution is to modify the boot loader, but I don't want to rebuild the SOF and it's really not necessary. On a boot (without reconfiguration because I cannot yet tell that I have reconfigured), if I detect a software image in the 2nd half of EPCS, the copy to over the factory image (in SDRAM) and do a software restart it does work. Now, if I can only detect at runtime that I reconfigured so I can do the copy if reconfigured.

Thank you for any information,

Bill A.