From: slavotinek@gmail.com   
      
   On 15.01.2023 17:58, Tomas Slavotinek wrote:   
   > On 15.01.2023 17:23, IBMMuseum wrote:   
   >> I just looked harder at my 'Type 2' Model 80 planar pictured at the   
   >> 'Ardent-Tool'; It has a bunch of bodge-wires - and a 386DX-16MHz CPU   
   >> with a 32MHz crystal on the planar! Now I need to look over my other   
   >> T2s - That one has been 16MHz the whole time!   
   >>   
   >> Maybe that explains an FRU difference...   
   >   
   > The CPU clock (among other signals) is derived from the 40 MHz   
   > oscillator U110. The 32 MHz oscillator U159 is used for the FPU (and   
   > other things).   
   >   
   > So, unless the board can be "jumpered" differently to change the clock   
   > source, I'd say somebody installed an incorrect CPU. Can you measure the   
   > clock frequency at the CPU CLK pin (or buzz the path out with the help   
   > of the schematic)?   
      
   E1 and E2 above the 32 MHz oscillator are dealing with the clock, but   
   only allow two configurations - synchronous where the FPU uses the 40   
   MHz CPU*2 clock, or asynchronous where it has its own 32 MHz source (if   
   the schematic is correct). I don't see a "jumper" in the CPU*2 path for   
   the 386.   
      
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