Read/Write I/O processor memory
|OSWord call||Action||Available on:|
|5||05||Read I/O processor memory||x||x||x|
|6||06||Write I/O processor memory||x||x||x|
A byte of I/O processor memory may be read or written across the Tube using this call. A 32 bit address should be contained in memory at the address contained in the X and Y registers.
For writes (OSWord 0x06) the value to write should be placed in XY+4
For reads (OSWord 0x05) the value read is placed in XY+4 on exit.
|XY+||Content||Read call||Write call|
|0||LSB of address in I/O processor|
|3||MSB of address in I/O processor|
|4||Byte read by OSWord 0x05||Byte to write with OSWord 0x06|
If the I/O processor uses 16 bit memory addressing only least significant two bytes need to be specified.