https://www.jensma.de/pirates/?gam=155#
111111
[5432109876543210]
1.xxPPPPPpCCCCCC
||||||||++++++- CHR bank
||++++++------- PRG bank
|+------------- mode (1=16K, 0=32K)
+-------------- mirroring (1=H, 0=V)
* There is also 4x 4bit memory latch (74670), mapped at $5800 (mask: $f800)
* One of the PRG memories must have positive chip enable as both share the same /CE and /OE pins