UM6558 and UM6559 pinout

UM6558 is PPU with additional 8 pins (CD0..CD7) that are used to output currently rendered pixel color.

            .--\/--.
     R/W -> |01  48| -- +5V
  CPU D0 <> |02  47| -> ALE
  CPU D1 <> |03  46| <> PPU AD0
  CPU D2 <> |04  45| <> PPU AD1
  CPU D3 <> |05  44| <> PPU AD2
  CPU D4 <> |06  43| <> PPU AD3
  CPU D5 <> |07  42| <> PPU AD4
  CPU D6 <> |08  41| <> PPU AD5
  CPU D7 <> |09  40| <> PPU AD6
*    /CS -> |10  39| <> PPU AD7
* CPU A2 -> |11  38| -> PPU A8
* CPU A1 -> |12  37| -> PPU A9
* CPU A0 -> |13  36| -> PPU A10
     GND ?? |14  35| -> PPU A11
     GND ?? |15  34| -> PPU A12
     GND ?? |16  33| -> PPU A13
     GND ?? |17  32| -> /RD
*    VCC ?? |18  31| -> /WR
*    CLK -> |19  30| -> CD0   *
*   /INT <- |20  29| -> CD1   *
*   /RST -> |21  28| -> CD2   *
*    CD7 <- |22  27| -> CD3   *
*    CD6 <- |23  26| -> CD4   *
*    GND -- |24  25| -> CD5   *
            '------'

• = difference with respect to the common 40-pin PPU pinout

UM6559 is DAC that is capable of generating RED/GREEN/BLUE/SYNC/CHROMA/LUMA signals from of the CD0..CD7 values

            .--\/--.
     CD4 -> |01  24| <- CD3
     CD5 -> |02  23| <- CD2
     +5V -- |03  22| <- CD1
      A1 -> |04  21| <- CD0
      A2 -> |05  20| -- GND
    LUMA <- |06  19| <- BIAS
   ?? NC -> |07  18| -> BLUE
    SYNC <- |08  17| -> GREEN
     CD6 -> |09  16| -> RED
     CD7 -> |10  15| -- +5V
     CLK -> |11  14| -> CHROMA
     GND -- |12  13| -> NC ??
            '------'

Sources:

• Emu-Land forum post with diagram showing difference between UM6558 vs UM6538
• Leaked short datasheet for UM6559
• Krzysiobal's reverse-engineering of UM6559 in isolation