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OS_UpdateMEMC
Programmer's Reference Manuals
» Part 15 – SWI Calls
» OS
» OS_UpdateMEMC
OS_UpdateMEMC
(SWI &1A)
| Entry | |
|---|---|
| R0 | New bits |
| R1 | Mask |
| Exit | |
|---|---|
| R0 | Old bits value |
| R1 | Old mask value |
Use
The purpose of this call is to read or write the contents of the MEMC control register.
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.
Reg = (RegCopy AND NOT R1) OR (R0 AND R1)
To read: R0,R1 = 0