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.