| SPARC | Sun-4 | Sun-4c | Sun-4m |
| Level 1 | SW1 | SW1 | SW1 |
| Level 2 | VME1 | SBus2 | SW2, VME1, SBus1 |
| Level 3 | VME2 | SBus3, SCSI | SW3, VME2, SBus2 |
| Level 4 | SW4, SCSI | SW4 | SW4, On-board SCSI |
| Level 5 | VME3 | SBus4, Ethernet | SW5, VME3, SBus3 |
| Level 6 | SW6, Ethernet | SW6 | SW6, On-board Ethernet |
| Level 7 | VME4 | SBus5, Video | SW7, VME4, SBus4 |
| Level 8 | Video | SBus6 | SW8, On-board Video |
| Level 9 | VME5 | SBus7 | SW9, VME5, SBus5 |
| Level 10 | System C/T | System C/T | SW10, System C/T |
| Level 11 | VME6 | Floppy | SW11, VME6, SBus6, Floppy |
| Level 12 | KBD/MS/SCC | KBD/MS/SCC | SW12, KBD/MS/SCC |
| Level 13 | VME7 | Audio | SW13, VME7, SBus7, Audio |
| Level 14 | Kernet C/T | Kernel C/T | SW14, Kernel C/T |
| Level 15 | Memory Error | Async Mem Error | SW15, Async Errors |