I built an Iomega ZIP100 parallel port emulator (PIC32MZ + USB disk images) – LPT100 project

A couple of years ago my old Iomega ZIP100 parallel port drive started randomly ejecting disks. Instead of replacing it, I decided to do something slightly unreasonable: reverse-engineer the protocol and build my own ZIP100 emulator. That hobby project eventually became LPT100, a parallel-port ZIP100 emulator implemented on a microcontroller that reads/writes disk images stored on a USB flash drive.

The project ended up being much deeper than expected because there is almost no public documentation of the ZIP parallel protocol. Most of the work involved reverse-engineering the Linux ppa driver, tracing PALMZIP behavior, and capturing port activity.

The final project, named LPT100, was implemented on a PIC32MZ microcontroller and tested with: MS-DOS/Windows 98/Windows XP/Linux (Super 8086 Box, DOSBox-X, QEMU) and MS-DOS + PALMZIP (Book 8088), with disk images stored on USB flash drive. Parallel port interface was done via GPIO + DMA capture.

I documented everything in two articles:

Part 1 – Protocol reverse engineering + emulator in DOSBox/QEMU

https://www.toughdev.com/content/2026/02/pic32mz-iomega-zip100-parallel-port-emulator-part-1-dosbox-qemu-testing/

Part 2 – Building the actual hardware

https://www.toughdev.com/content/2026/03/pic32mz-iomega-zip100-parallel-port-emulator-part-2-hardware-design/

Part 1 Video - Emulator testing (DOSBox + QEMU + multiple OSes):

https://youtu.be/ZMJkRygU8kI

Part 2 Video - Real hardware LPT100 board running on Book 8088:

https://youtu.be/340J7vItfPw

On my Book8088 system, write speed is ~7.2 KB/s, read speed is around 6.3 KB/s in nibble mode, which is actually pretty close to real ZIP parallel performance on 8088 systems. When tested in Windows 98 using DOSBox-X, the speed is around 50-60KB/sec in bidirectional mode. The emulator works perfectly on 8088-class systems, although faster machines (386+) can overwhelm the microcontroller timing. I might consider migrating to a faster MCU (e.g. Teensy) in a future revision.

If anyone here still uses parallel ZIP drives, I would love to hear your thoughts.