; > &.Doc180.IIC

Title:          IIC/1
Description:    This document describes the IIC module in RISC OS 2.00

A module "IIC" in RISC OS 2.00 allows reading and writing to IIC devices
which may be attached to podules, as well as to the internal CMOS RAM/clock
chip.

SWI IIC_Control (&240)
----------------------

in:     R0 = device address (bit 0 set => read operation, clear => write)
        R1 -> data block
        R2 = length of data block

out:    V=0 => successful operation; all registers preserved; for a read
               operation, the data block is updated
        V=1 => error; R0 -> error block; for a read operation, data block
               possibly partly updated

Possible errors to-date
-----------------------
"No acknowledge from IIC device", error number &20300: the device failed to
acknowledge, either to the device address, or during the data transfer.