How Windows 98 Supported External Zip Drives

Microsoft Windows 98 supported external Iomega Zip drives through a combination of legacy parallel port interfaces and emerging Universal Serial Bus (USB) technology. While parallel port models bridged older PC hardware using specialized device drivers and port pass-through techniques, the introduction of USB support in Windows 98 revolutionized how removable media operated by enabling hot-plugging and faster data transfers. This article examines the technical mechanisms, driver architectures, and system configurations Windows 98 used to interface with both types of external Zip drives.

Parallel Port Zip Drive Support

The parallel port Zip drive, known as the Zip 100 Parallel, was designed for computers lacking internal SCSI or IDE expansion options. Because parallel ports were originally designed for one-way printer output rather than bidirectional mass storage, Windows 98 required specific driver layers to enable high-speed data communication.

  1. Driver Architecture: Windows 98 utilized specialized mini-port drivers, primarily PPA.SYS or PPA3.SYS, alongside Advanced SCSI Programming Interface (ASPI) routing. These drivers allowed the operating system to communicate with the drive's internal SCSI-to-parallel conversion chip.
  2. Port Modes in BIOS: Performance depended heavily on the host PC's BIOS settings. Windows 98 could interact with standard unidirectional ports, but it achieved optimal speeds when configured for Enhanced Parallel Port (EPP) or Extended Capabilities Port (ECP) modes, which significantly raised bandwidth closer to the drive's physical capabilities.
  3. Daisy-Chaining and Pass-Through: External parallel Zip drives included a pass-through port so users could connect a printer to the back of the drive. The Windows 98 parallel driver arbitrated traffic between the storage device and the printer to prevent device collisions, though printing while writing large files often degraded performance.

USB Zip Drive Support

The launch of Windows 98, and particularly Windows 98 Second Edition (SE), coincided with the transition to USB. USB Zip drives offered substantially easier setup and higher transfer rates compared to parallel ports.

  1. Windows Driver Model (WDM): Windows 98 introduced WDM support for USB controllers, allowing real-time peripheral detection. Unlike modern operating systems, early Windows 98 did not have a universal, out-of-the-box USB Mass Storage Class driver. Users typically had to install an INF file and proprietary vendor drivers, such as IOMUSB.SYS, during the initial setup.
  2. Plug and Play and Hot-Swapping: Once the necessary drivers were registered, Windows 98 fully supported hot-plugging the USB Zip drive. The operating system dynamically detected the peripheral insertion, initialized the drive without requiring a system reboot, and mounted it as a removable drive in "My Computer."
  3. Power and Bandwidth: USB 1.1 provided up to 12 Mbps of bandwidth, offering superior read and write speeds over standard parallel ports. While some portable USB Zip drives could run on bus power, desktop units still utilized external power adapters to satisfy the mechanical demands of the spinning magnetic media.

Integration with the Operating System

Regardless of whether the drive connected via parallel or USB, Windows 98 treated the Zip drive as standard removable media with a dedicated drive letter. The operating system mapped files using either FAT16 (standard for 100MB disks) or FAT32, allowing standard Windows Explorer file operations such as drag-and-drop.

To expand native functionality, users commonly installed the "IomegaWare" software suite. This software integrated directly with the Windows 98 shell, adding right-click options for software-based disk ejection, write protection, and disk diagnostics.