Help identifying 1.5MB trapdoor expansion board with Gary chip adapter for Amiga 500

[xavicampa]

It reports as 1.5MB slow fast ram.

It seems to have 4 “jumpers” under the Gary adapter, tagged P1, P2, P3 and P4 (P1 and P2 closed, P3 and P4 open), and a via close to the cable connector (provision for a pin to connect to JP2?).

I haven’t been able to find it in the Amiga Hardware databases available online, nor Google.

Any pointers?

Thanks in advance!

 

[giobbi]

there's a similar project on PCBway:
https://www.pcbway.com/project/shareproject/DIY_AMIGA_500_2MB_RAM_EXPANSION__RETRO_VERSION_.html
Yours seems to have the RTC too, since there's a battery.