Lovely little mapper ths one is:
PIN 3 is truly NC. Pin 18 is connected internally but I don't know what it is for.
Code:
.----\/----.
(s) PRG D3 <-> |01 44| <-> PRG D2 (s)
(r) PRG A18 <- |02 43| <-> PRG D4 (s)
NC - |03 42| <-> PRG D1 (s)
(n) M2 -> |04 41| <-> PRG D5 (s)
(n) PRG A13 -> |05 40| <-> PRG D0 (s)
GND - |06 39| - +5v
(n) PRG A14 -> |07 38| <-> PRG D6 (s)
(n) PRG /CE -> |08 37| <-> PRG D7 (s)
(n) PRG R/W -> |09 36| -> PRG A13 (r)
(n) /IRQ <- |10 35| -> PRG A16 (r)
(r) CHR /RD -> |11 34| -> PRG A14 (r)
(r) CHR A10 -> |12 33| -> PRG A15 (r)
(s) CHR A11 -> |13 32| -> PRG A17 (r)
(s) CHR A12 -> |14 31| -> PRG /CE (r)
(s) CHR A13 -> |15 30| -> WRAM /CE (w)
(r) CHR /CE -> |16 29| -> WRAM CE (w)
+5v - |17 28| - GND
NC - |18 27| - +5v
(r) CHR A10 <- |19 26| -> CHR A17 (r)
(r) CHR A16 <- |20 25| -> CHR A15 (r)
(r) CHR A11 <- |21 24| -> CHR A14 (r)
(r) CHR A13 <- |22 23| -> CHR A12 (r)
`----------'
(s) PRG D3 <-> |01 44| <-> PRG D2 (s)
(r) PRG A18 <- |02 43| <-> PRG D4 (s)
NC - |03 42| <-> PRG D1 (s)
(n) M2 -> |04 41| <-> PRG D5 (s)
(n) PRG A13 -> |05 40| <-> PRG D0 (s)
GND - |06 39| - +5v
(n) PRG A14 -> |07 38| <-> PRG D6 (s)
(n) PRG /CE -> |08 37| <-> PRG D7 (s)
(n) PRG R/W -> |09 36| -> PRG A13 (r)
(n) /IRQ <- |10 35| -> PRG A16 (r)
(r) CHR /RD -> |11 34| -> PRG A14 (r)
(r) CHR A10 -> |12 33| -> PRG A15 (r)
(s) CHR A11 -> |13 32| -> PRG A17 (r)
(s) CHR A12 -> |14 31| -> PRG /CE (r)
(s) CHR A13 -> |15 30| -> WRAM /CE (w)
(r) CHR /CE -> |16 29| -> WRAM CE (w)
+5v - |17 28| - GND
NC - |18 27| - +5v
(r) CHR A10 <- |19 26| -> CHR A17 (r)
(r) CHR A16 <- |20 25| -> CHR A15 (r)
(r) CHR A11 <- |21 24| -> CHR A14 (r)
(r) CHR A13 <- |22 23| -> CHR A12 (r)
`----------'
PIN 3 is truly NC. Pin 18 is connected internally but I don't know what it is for.