Um8250b

Asynchronous Communication Element (ACE)

Pinout

DIP40
         +---\/---+
      D0 | 1    40| Vdd
      D1 | 2    39| *RI
      D2 | 3    38| *DCD
      D3 | 4    37| *DSR
      D4 | 5    36| *CTS
      D5 | 6    35| MR
      D6 | 7    34| *OUT1
      D7 | 8    33| *DTR
    RCLK | 9    32| *RTS
     SIN |10    31| *OUT2
    SOUT |11    30| INTRPT
     CS0 |12    29| NC
     CS1 |13    28| A0
    *CS2 |14    27| A1
*BAUDOUT |15    26| A2
   XTAL1 |16    25| *ADS
   XTAL2 |17    24| CSOUT
  *DOSTR |18    23| DDIS
   DOSTR |19    22| DISTR
     Vss |20    21| *DISTR
         +--------+

Frequency

DIP40
Set reader to FREQ, put black probe to GND, red probe to 16 and to 17 to measure CPU clock

Files

• 
  UM8250B Datasheet