|R0||Old speed value|
|R1||New speed value|
The purpose of this call is to set the processor speed.
The new speed is set as:
New value = (old speed AND R1) EOR R0
Currently supported speed settings are:
Some hardware allows programs to exert more control over the CPU speed by SWI Portable_Speed2 to specify what clock rates the ‘slow’ and ‘fast’ speed settings equate to.