Document system "using" (reserved) area

[spth]

The Padauk µC have a "system using" (stated like that in the manual) i.e. reserved area at the end of the program memory. depending on the type it is 8 to 32 words.
The Chinese IDE manual has some information on the 8-word variant (apparently it contains a checksum, a rolling code, oscillator calibration data and "code option"s (whatever they are).

But it would be good to have exact documentation for all devices.

Philipp

P.S.: The file Last8W.html contained in the IDE documentation has some information on the 8-Word variant. too. Depending on support for the ltabl/ltabh instructions, the rolling code is either 16 bit per entry or 8 bit per entry (with each byte encoded in a ret b instruction, so each byte can be read by a call into the rolling code. The code option is apparently a 5-valued voltage vs. speed choice and a three-valued "security" setting.

[freepdk]

First step was done by dumping the content of a real IC written with official WRITER.

(see http://www.eevblog.com/forum/blog/eevblog-1144-padauk-programmer-reverse-engineering/msg2019274/#msg2019274 )

[freepdk]

I also did some more tests.
First results here:
https://github.com/free-pdk/fppa-pdk-documentation/blob/master/Reserved_Area_Last_8_Words_Of_Codemem.txt