+---------+
  | . . . . |   (at the Calculator)
  \---------/
    1 2 3 4
| Pin | Name | Dir | Description | 
|---|---|---|---|
| 1 | - | - | - | 
| 2 | TXD | OUT | Transmit Data | 
| 3 | RXD | IN | Receive Data | 
| 4 | GND | - | Ground | 
Contributor: Joakim Ögren
  Source:
  ?
  Copyright © The Hardware Book Team 1996-2001.
  May be copied and redistributed, partially or in whole, as appropriate.
 Document last modified: 2000-07-09