| Pin | Symbol | Description | 
|---|
| 1 | D0 | data bus | 
| 2 | D1 | data bus | 
| 3 | D2 | data bus | 
| 4 | D3 | data bus | 
| 5 | D4 | data bus | 
| 6 | D5 | data bus | 
| 7 | D6 | data bus | 
| 8 | D7 | data bus | 
| 9 | RCLK | receiver clock input (16x baud rate) | 
| 10 | RX | serial input | 
| 11 | TX | serial output | 
| 12 | CS0 | chip select (active high) | 
| 13 | CS1 | chip select (active high) | 
| 14 | CS2 | chip select (active low) | 
| 15 | BAUDOUT | baud rate generator output | 
| 16 | XIN | external crystal input | 
| 17 | XOUT | external crystal output | 
| 18 | WR | write enable (active low) | 
| 19 | WR | write enable (active high) | 
| 20 | GND | ground | 
| 21 | RD | read enable (active low) | 
| 22 | RD | read enable (active high) | 
| 23 | DDIS | driver disable | 
| 24 | TXRDY | TX DMA signal | 
| 25 | ADS | address strobe input | 
| 26 | A2 | register select | 
| 27 | A1 | register select | 
| 28 | A0 | register select | 
| 29 | RXRDY | RX DMA signal | 
| 30 | INTR | interrupt output (active high) | 
| 31 | OUT2 | general purpose output | 
| 32 | RTS | request to send (output to modem) | 
| 33 | DTR | data terminal ready (output to modem) | 
| 34 | OUT1 | general purpose output | 
| 35 | MR | master reset (active high) | 
| 36 | CTS | clear to send (input from modem) | 
| 37 | DSR | data set ready (input from modem) | 
| 38 | DCD | data carrier detect (input from modem) | 
| 39 | RI | ring indicator (input from modem) | 
| 40 | Vcc | supply voltage |