IBM 6128291 WD-3158 6128263 120MB MCA ESDI 3.5in Hard Disk Drive HDD PS/2

IBM 6128291 WD-3158 6128263 120MB MCA ESDI 3.5in Hard Disk Drive HDD PS/2

The IBM WD-3158 is a 120MB 3.5-inch hard drive built for IBM PS/2 systems using the Micro Channel Architecture (MCA) bus. It connects directly to the MCA slot and uses an ESDI (Enhanced Small Device Interface) internal architecture. Made by IBM Japan Ltd., this drive carries IBM part number 6128263 and FRU part number 6128291, and was manufactured for use in IBM PS/2 workstations and servers of the era.

Specifications & What's Included

• Brand: IBM (Made by IBM Japan Ltd.)
• Model: WD-3158
• P/N: 6128263
• FRU P/N: 6128291
• MLC: C27850
• Capacity: 120 MB
• Form Factor: 3.5-inch
• Interface: MCA (Micro Channel Architecture) / ESDI
• Edge Connector: MCA gold-finger bus connector (visible on PCB)
• Drive only — no cables or mounting hardware included

Applications

The Micro Channel Architecture (MCA) was IBM's proprietary 32-bit bus introduced in 1987 with the PS/2 product line, replacing the older ISA bus in IBM's higher-end systems. MCA hard drives like the WD-3158 connected directly to the MCA slot, integrating the drive controller into the system board or a dedicated MCA adapter rather than requiring a separate ISA controller card. ESDI (Enhanced Small Device Interface) was a common internal drive technology of the late 1980s and early 1990s, offering faster transfer rates and larger capacities than the earlier ST-506/412 standard. IBM PS/2 systems that used MCA storage included models such as the PS/2 Model 50, 55, 60, 70, 80, and 90 — popular in business, government, and institutional environments of the era. Today these drives are sought by collectors and technicians maintaining vintage IBM PS/2 hardware.