Mac               Processor/Speed     Rom    RAM      Disk Drives    Hard Drives

Mac II            68020      16MHz    1M    2M-128M    800K         20-500meg SCSI
Mac IIx           68030      16MHz    1M    4M-128M    1.4M         20-500meg SCSI
Mac IIcx          68030      25MHz    1M    4M-128M    1.4M         20-500meg SCSI
Mac IIci          68030      25MHz    4M    4M-128M    1.4M         20-500meg SCSI
Mac IIsi          68030      20MHz    4M    4M-128M    1.4M         20-500meg SCSI
Mac IIfx          68030      40MHz    4M    4M-128M    1.4M         20-500meg SCSI

Useable Systems: System 6.X reqires up to 8megs; System 7.X require minimun of 4megs. 

Note:
     Mac II, IIx, IIcx, SE30 share the same Rom Set, which requires Mode32 w/System 7 to recognize more than 8megs.
     Mac IIci, IIfx are 32bit clean, and do not require Mode32 w/System 7 to recongize Ram configurations over 8megs.
     Mac IIcx & ci has 3 NuBUS expansion slots, ci has an additional PDS slot     
     Mac II, IIx, IIfx has 6 NuBUS slots, IIfx has an additional PDS slot
     Mac IIsi, has 1 PDS slot.
     Both Mac IIci & si have an internal 8bit video, which reduces Ram size by 1meg if used.
     If internal video is used on Mac IIci, speed drops 25%.