ملف:IBM PS2 MCA Model 55 SX, slot riser card.jpg

English: Internal design of the IBM PS/2 Model 55 SX, showing the Micro-Channel Architecture slot riser card. The edge connector across the top supplied power and data to the single internal hard drive that a PS/2 could accept. It is interesting to note that the hard drive appears to connect straight to the MCA bus without any interceding drive controller electronics. IBM called this Direct Bus Attachment (DBA), and most common was DBA ESDI that emulated a PS/2 ESDI controller.