IMPORTANT NOTE - read before defining CFG_USE_OSCCLK in your board		 config file!!!WARNING: Wrong settings of this parameter have the potential todamage hardware by running the MBX's CPU at frequencies that exceedit's rating and/or overdriving the it's SPLL!Ramblings:1) Motorola offered 12 different variants of the MBX, 6 823s and 6 860s.2) Of these 12 variants, only 2 were entry level boards.3) I believe that the 2 entry level boards were the only ones that   used OSCM clocking. I can't be completely certain of this at this   point.4) Motorola never offered an MBX that ran faster than 50Mhz.5) The 10, non-entry level boards, ran at 40Mhz.6) The EXTCLK input has a minimum clock of 15Mhz for the 823/860.7) Motorola no longer sells MBXs.Based on this information, I can surmise that the default power-onreset clocking was one of the following three options.Multiplier       SPLL Options------------------------------------513              OSCM is SPLL input5                OSCM is SPLL input1                EXTCLK is SPLL inputThe forth option:5                EXTCLK is SPLL inputis not possible on MBXs. This is because the minimum EXTCLK inputfrequency is 15Mhz. 5 * 15Mhz = 75 Mhz. There was no variant that ranabove 50 Mhz.The board I have borrowed definitely uses a multiplier of 1 forEXTCLK and runs at 40Mhz. I even went so far as to put a scope on it.One of the two default OSCM modes are most likely what was used onthe entry level boards to cheapen them by eliminating the externalcrystal oscillator.To add insult to injury, the stupid 860 PLPRCR register retains it'smultiplication factor through hard resets. You can't clear it outbecause it is battery backed and once it is set wrong, it stayswrong. The only way to reset it, so that it takes on it's defaultmultiplier is to disconnect all power including external, batteries,as well discharging caps on the board. This precludes the fact thatyour 860 may be quite DEAD by this time!If you don't setup the multiplication factor for boards that use theOSCM input, they won't run correctly, but at least they won't bedead.Addtionally, there is no good way to determine the clock input sourcefrom CPU register data. The only way to deal with this is either hardcode it, determine the correct value with some rather NASTY timingloops, or try to grok it from external data sources. Motorolafirmware opts for the NASTY timing loops, but needs to configure theserial ports to do so.You may have a legitimate need to define CFG_USE_OSCCLK if yourMBX8xx board is using the OSCM clocking mode.You better know what you are doing here.