The Penbex OS ROM dump from a Palm Vx fitted with a 4MB flash chip, flashed to the P528SM's update file using the EPD30 bootloader (part of the EPD30 ROM also available here - go look at that page!), trimmed back to 2MB. The P528SM is part of a series of devices by Surwin (which seems to be the original manufacturer of this hardware) that was rebranded by countless others, running different OSes. Other models are the basic B528, and intermediary P528. It is very similar in hardware to a Palm IIIxe, but with the addition of SD and mp3 decoding/audio output hardware. Other versions of the 528 series omit these. Penbex was shipped on a handful of devices mostly meant for the Asian market, and has almost completely vanished. The 528 seems to have sold well in Europe, and was also sold in North America as the Empower PowerPlay V (running LinuxDA, also available here)

This should boot on any IIIx-like device with a 68EZ328. It also runs, somewhat incorrectly (buttons improperly mapped, backlight always on) on the Palm V(x).

At least on the Vx, it complains of a low battery and immediately shuts off. This is probably to be expected - the 528 has li-ion batteries implemented differently from Palm's.

(grm is on the lookout for 528 hardware - if you have something like the pic in the article, please reach out via palmdb discord)

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