The PFDBK Disk Unit Emulator

Front This is an implementation of William R Cooke's floppy emulator for the Arduino line of microcontrollers. William created this in 2019, but only in 2023 I build my own version.
The code is functional identical to the original from William, but some extensions like changing disk images via the debug/programming interface. For the PX-4 there are programs to do the same via the serial port. My implementation is based on the Arduino Pro Micro, but it is tested for the Mega 2560 too.
Other differences are the blinking lights indication (SD-card) access per mounted disk image and the SERIAL port activity.

Back The back side contains the connections to PX-4/PX-8 the power input (optional the host interface) and the reset button. The host interface allows changing the configuration; which disk image is mounted on which drive and a disk-level write protect. These are the functionality to be controlled from the PX-4/PX-8, but that functionality still has to be build.
The wiring to the PX-4/PX-8 requires a #725-F9 cable (the original #725 has a 25 pin connector). The host interface can be used to configure the drive mapping.

Inside Lots of space inside, but a smaller case, can become a problem with stiff cables.
There are two options for the serial port; all components on the PCB or a breakout with a MAX232, capacitors and sub-DE 9 pin.
The SD-card is always on a breakout board, the HW-203. Only a single row of headers is needed between main board and breakout, use the combination that best aligns with the front panel.

Changes to the PFBDK firmware

The Arduino sketch is modified to run on both the Arduino Pro Micro and Arduino Mega 2560. Some new commands were added to the EPSP functions to support some management of the images on the SD-card.

The files in the root directory of the SD-card can be listed, mounted on the drives, and set to write protected. New, empty images can be generated.

Some PX-4 specific programs are created to manipulate the SD-card:

pfdir4 [n] - lists the files in the root directory of the SD card. The output is eight file names per part, the ENTER or SPACE key can be used to fetch the next part. The optional part number specifies the start part.
pfmnt4 [d] [ffffffff.eee] - mounts file ffffffff.eee on drive d. No arguments show the current 'mount table'.
pfwp4 [d] [s] - sets drive [d] to write protect state [s]. s = 0 for off and 1 = on. No arguments show the current write protect state for all four drives.
pfnew4 ffffffff.eee - generates a new and empty image file in the root directory of the SD-card

More information on the Github page with my fork of the Arduino sketch

Local links:

Schema of the Mega 2560 experiment shield version
Schema of the Pro Micro PCB
Schema of the Pro Micro PCB, with RS-232-c port fix
The cereal PX8 and PXDock archives unpacked into 20 images
TF-20 page,
PX-4 page,
PX-8 page,
Epson Serial Protocol used between TF-20 and HX-20, PX-8, PX-4,
3D-printer files. Open SCAD & STL's.
KiCAD files for the Arduino Pro Micro board version 1.0. It works well, but no chaining / multi-device suppert.

External links:

Last update: 2024-12-16

fjkraan@electrickery.nl

Front		This is an implementation of William R Cooke's floppy emulator for the Arduino line of microcontrollers. William created this in 2019, but only in 2023 I build my own version. The code is functional identical to the original from William, but some extensions like changing disk images via the debug/programming interface. For the PX-4 there are programs to do the same via the serial port. My implementation is based on the Arduino Pro Micro, but it is tested for the Mega 2560 too. Other differences are the blinking lights indication (SD-card) access per mounted disk image and the SERIAL port activity.
Back		The back side contains the connections to PX-4/PX-8 the power input (optional the host interface) and the reset button. The host interface allows changing the configuration; which disk image is mounted on which drive and a disk-level write protect. These are the functionality to be controlled from the PX-4/PX-8, but that functionality still has to be build. The wiring to the PX-4/PX-8 requires a #725-F9 cable (the original #725 has a 25 pin connector). The host interface can be used to configure the drive mapping.
Inside		Lots of space inside, but a smaller case, can become a problem with stiff cables. There are two options for the serial port; all components on the PCB or a breakout with a MAX232, capacitors and sub-DE 9 pin. The SD-card is always on a breakout board, the HW-203. Only a single row of headers is needed between main board and breakout, use the combination that best aligns with the front panel.