The GPIO signals GP0[7:0] and GP1[7:0] from the ARM926PXP development chip are connected to the interface connector as shown in Figure 3.22. This enables you to use the GPIO signals with custom logic you implement in an interface board.
See also General Purpose Input/Output, GPIO, the ARM926EJ-S Development Chip Reference Manual and the ARM PrimeCell GPIO (PL061) Technical Reference Manual.
The GPIO signals GP2_[3:0] are connected to the boot select switch S4.
GP2_ is HIGH if an interface board is connected.
GP2_[6:5] go to the battery pack connector.
There are no external connections for GP3 from the ARM926PXP development chip.