Personal IRIS 4D/25 front view. 
Front Drive Door reveals: two half height drive bays, power switch, reset button, power indicator, and dreaded fault light. One drive bay is loaded with a CDROM drive. 
Totally Front Loading Unit (TFLU) incorporated an access panel for the system drive. NOTE: all drives must have drive sleds. 
Pop the system drive out. 
Here's the back. The round handle is the case latch. 
The case come in two pieces. The one removed here reveals the EMOD. The other reveals the power supply, and for non TFLU cabinet styles (ie early 4D/20's) the captive system drive. 
The EMOD tilts out so you can remove the cables from the top before pulling it out of the cabinet. 
Once out of the cabinet, the EMOD houses a Processor and I/O side. Note there are 16 slots for SIMMs, four are populated here. Also a 6U VME style card slot is provided. 
 
 
The other side of the EMOD houses graphics.The Personal IRIS has 24bit,  hardware z-buffer, and Turbo graphics.