void (*fnIAP)() = 0xFFF0;

// Load parameters.
DPL = (unsigned char) CMD_uiCmdHexParameter;
DPH = (unsigned char) (CMD_uiCmdHexParameter>>8);

// Need to load registers r0 and r1 with the clock rate and the command.
#pragma asm
MOV A, XTAL_MHZ
MOV r0, A
MOV A, IAP_CMD_READ_BYTE
MOV r1, A
#pragma endasm

// Pet watchdog for IAP/ISP test. (Period min 500 ms)
XTR_mWATCHDOG();

// Disable interrupts.
EA = 0;

// Enable the BootRom. I'm guessing this is a shadow register.
AUXR1 |= 0x20;

// Need to jump to IAP function call.
fnIAP();

// Disable the BootRom.
AUXR1 &= ~0x20;

// Re-enable interrupts.
EA = 1;

// Need to return the value read from the accumulator.
SRL_fnLoadHexIntTxBuf(ACC);
SRL_fnStartTx();