Processor     PC Model      Cycle Time                                          
---------   -------------   ----------                                          
   ??       PC/1                                                                
  8086      PC/XT                                                               
  8086      PC/AT                6                                              
                                 8                                              
                                10                                              
   286      PS/2 Model 50       16?                                             
                                20?                                             
   386      PS/2 Model 80       16    Red Power Switch                          
                                20    White Power Switch                        
                                25    White Power Switch                        
   486      PS/2 Model 70       25                                              
            PS/1                33                                              
                                50                                              
                                66                                              
   486      Thinkpad            75