M50805 pinout

Mitsubishi M50805: 22-pin 0.4" PDIP (Used in one mapper 3 game)

                 .--\/--.
           NC -- |01  22| -- NC
           NC -- |02  21| -- NC
           NC -- |03  20| -- NC
    DREQ/TEST <- |04  19| <- /D0
  MODE \  MS1 -> |05  18| <- /D1
SELECT /  MS0 -> |06  17| <- /D2,DTIN
         XOUT <- |07  16| -> BUSY
          XIN -> |08  15| <- /SYNC
          /CE -> |09  14| -> DA1 \ DA
       /RESET -> |10  13| -> DA0 / OUTPUT
          +5V -- |11  12| -- GND
                 '------'

Sources: [1], [2]

The die shot shows that pins 1-3 and 20-22 are genuinely no connection - there's nothing to be wire bonded to.