The Psion 5mx PRO has no embedded OS in the Mask ROM, unlike other machines. It has only a small (128 KB) BootLoader chip.
It's an AT29LV010A Flash, attached to the CS7 signal.
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Normally, the device at CS7 is mapped to address 0x70000000, but in PRO, unlike other 5mx machines, MCU (Windermere) runs in Alternate Test ROM (yep, Test!).
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So this actually reverses the address mapping for all devices (ETNA and PCMCIA interface too), and now BL Flash is at 0x00000000, and the machine can boot from it.
(There is no Windermere documentation, but CL-PS7110 (used in Series 5) has a similar mode).
Normally, there is no access to the BootLoader chip from the OS, as it's not MMU-mapped.
A special version of the standard 5mx PRO OS (Build 319) is modified to be able to dump this BootLoader Flash chip.
If you have a machine with BootLoader different than "S5mx BLGE v109" (check the sticker on the chip); please dump it using the following steps:
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Run PsiROMx (embedded);
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Open Advanced options;
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Set Start address at 51200000;
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Set Size (KB) to 128, End address must be at 51220000;
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Select Save ROM, set name (for example: sys$bl.bin);
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Wait until dumping is done;
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Check the file size, it must be 128 KB or 131072 Bytes;
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If all is ok, offer your file to this repository.
You can also dump your EEPROM (128 Bytes). Unpack additional software by installing Special Tools.SIS, then run Show EEPROM.exe (at C:\) to list your EEPROM's contents to the screen. Take a photo or make an MBM screenshot (Shift + Ctrl + Fn + S) and offer it to bs0dd@bs0dd.net.
For advanced users: there is also an ARLO tool (Linux loader for Psions) in the Special Tools pack. It's not configured to run Linux, but it's included due to the advanced and expert modes functionality. You can use it for reading and researching some memory sections. Enjoy!
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