h6. [[Portable]] h6(. » [[Portable SWI Calls|SWI Calls]] h6((. » [[Portable_Speed2]] h6(((. » Portable_Speed2 7 h2. Portable_Speed2 7 h5. (SWI &42FCE) |_<^{width:4em}. Entry | | |<^. R0 |<^. 7 (Reason code) | |_<^{width:4em}. Exit | | |<^. R0 |<^. Current CPU speed, as an index | h4. Use The purpose of this call is to read the current CPU speed, as an index into the list of available speeds. To instead read the CPU speed as a MHz value, use [[Portable_Speed2 0]]. h4. Notes Due to hardware restrictions or for performance reasons, most systems will only support a limited number of CPU clock rates. [[Portable_Speed2 4]], [[Portable_Speed2 5]], and [[Portable_Speed2 6]] allow the user to enumerate the list of available clock rates. Index 0 is always the slowest available speed, and (return value of [[Portable_Speed2 4]])-1 is always the highest available speed. There is no direct method available to set the CPU speed to a desired value. Instead programs must use [[Portable_Speed2 2]] (or [[Portable_Speed2 8]]) to set the desired 'slow' and 'fast' speeds, and then [[Portable_Speed]] to switch to the desired speed. h4. See also * [[Portable_Speed]] * [[Portable_Speed2]] * [[Portable_Speed2 0]] * [[Portable_Speed2 2]] * [[Portable_Speed2 4]] * [[Portable_Speed2 5]] * [[Portable_Speed2 6]] * [[Portable_Speed2 8]] * [[Portable SWI Calls]]