4 pin HP48 calculator special connector at the calculator
The HP48 and HP95 calculators share a proprietary 4-pin serial connector fitted on the calculator body for data transfer with a PC or other devices. The connector layout is specific to these HP calculator models and carries standard serial transmit, receive, and ground signals. Only the four pins listed below are defined for this interface.
| Pin | Name | Dir | Description |
|---|---|---|---|
| 1 | - | - | - |
| 2 | TXD | OUT | Transmit Data |
| 3 | RXD | IN | Receive Data |
| 4 | GND | - | Ground |
Notes
Pin numbers refer to the connector on the calculator; pins not listed are unused.