h6. [[OS SWI Calls]] h6(. » OS_UpdateMEMC h2. OS_UpdateMEMC h5. (SWI &1A) |_<^{width:4em}. Entry | | |<^. R0 |<^. New bits | |<^. R1 |<^. Mask | |_<^{width:4em}. Exit | | |<^. R0 |<^. Old bits value | |<^. R1 |<^. Old mask value | h4. Use The purpose of this call is to read or write the contents of the MEMC control register. h4. Notes This SWI programs individual bits in the MEMC control register, on machines still supporting Acorn's custom chipsets. Since the MEMC is write-only, this is done via a software copy, maintained by the OS. <code>Reg = (RegCopy AND NOT R1) OR (R0 AND R1)</code><br /> To read: R0,R1 = 0