32-Bit Disk Access and Western Digital 1003 Controller Cards

• Microsoft Windows operating system versions 3.1, 3.11

SUMMARY

The Microsoft Windows version 3.1 32-Bit Disk Access feature actually performs 16-bit input/output with the Western Digital 1003 hard drive controller card and compatibles.

MORE INFORMATION

Microsoft Windows 3.1 ships with one Virtual Hard Disk Controller Device, which is WDCTRL. WDCTRL supports hard-drive controllers that are compatible with the Western Digital 1003 standard. This standard is a 16-bit standard.

The 32-Bit Disk Access feature is a series of layered virtual device drivers. The higher-level virtual device drivers send their requests down to the virtual device driver, which actually talks to the hard disk controller, that is, WDCTRL. The communication between virtual device drivers is 32-bit data. The virtual device driver that communicates to the hard disk controller can use 16-bit or 32-bit input/output.

Currently WDCTRL is using 16-bit input/output because it was written specifically for the Western Digital 1003 16-bit standard. To achieve true 32-bit input/output, a hardware manufacturer would have to write a low-level virtual device driver that communicates to a specific hard drive controller that is 32-bit. Currently Microsoft only provides the WDCTRL.