8530, 8531, Z8530, Z8531
Zilog Serial Comminucations Controller.
(Z8531 has no synchronous capabilities)

          +--------------+
       D1 |1    +--+   40| D0
       D3 |2           39| D2
       D5 |3           38| D4
       D7 |4           37| D6
     /INT |5           36| /RD
      IEO |6           35| /WR
      IEI |7           34| A0 A/B
   /INTAK |8           33| /CE
      VCC |9           32| A1 D/C
  /W_REQA |10   Z8530  31| GND
   /SYNCA |11    SCC   30| /W_REQB
   /RTxCA |12          29| /SYNCB
     RxDA |13          28| /RTxCB
   /TRxCA |14          27| RxDB
     TxDA |15          26| /TRxCB
/DTR_REQA |16          25| TxDB
    /RTSA |17          24| /DTR_REQB
    /CTSA |18          23| /RTSB
    /DCDA |19          22| /CTSB
      CLK |20          21| /DCDB
          +--------------+

    Source: geocities.com/siliconvalley/peaks/3938

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