The sample performs a test on all on board and off board peripherals
of Zkit-51 mother board. Each test continues infinitely and can be
skipped by pressing the INTR key. Short messages describing the test
process are displayed on the LCD panel for the user's comfort. Queries
can be sent to info@zilogic.com. 

RTC test takes a backup of the timer registers and rewrites it back
after test.

SPI takes a backup of the first 10 bytes before writing to them. The
data is written back after the test.