16550
Asynchronous serial interface controller with DMA support and 16-byte FIFOs.
+-----+--+-----+
D0 |1 +--+ 40| VCC
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
RxD |10 16550 31| /OUT2
TxD |11 30| INTR
CE0 |12 29| /RXRDY
CE1 |13 28| A0
/CE2 |14 27| A1
/CLKOUT |15 26| A2
X1 |16 25| /ADS
X0 |17 24| /TXRDY
/WR |18 23| DDIS
WR |19 22| RD
GND |20 21| /RD
+--------------+

16552
Dual asynchronous serial interface controller with DMA support and 16-byte FIFOs, and an 8-bit parallel printer port.
PLCC68
+---------------+---------------+---------------+---------------+
| 10 2TxD | 27 GND | 44 1BD | 61 /2RXRDY |
| 11 /2DTR | 28 /1CTS | 45 1INT | 62 2RxD |
| 12 /2RTS | 29 /1DCD | 46 PD7 | 63 /ERR |
| 13 /2CTS | 30 /1RI | 47 PD6 | 64 VCC |
| 14 D0 | 31 /1DSR | 48 PD5 | 65 SLCT |
| 15 D1 | 32 /1CE | 49 PD4 | 66 BUSY |
| 16 D2 | 33 A2 | 50 PD3 | 67 PE |
| 17 D3 | 34 A1 | 51 PD2 | 68 /ACK |
| 18 D4 | 35 A0 | 52 PD1 | 1 PEMD |
| 19 D5 | 36 /WR | 53 PD0 | 2 2TR |
| 20 D6 | 37 /RD | 54 GND | 3 /2CE |
| 21 D7 | 38 /PCE | 55 /STB | 4 CLK |
| 22 /1TXRDY | 39 /RST | 56 /AFD | 5 /2DSR |
| 23 VCC | 40 VCC | 57 /INIT | 6 /2RI |
| 24 /1RTS | 41 1RxD | 58 /SLIN | 7 GND |
| 25 /1DTR | 42 /2TXRDY | 59 PINT | 8 /2DCD |
| 26 1TxD | 43 /ENIRQ | 60 2INT | 9 /1RXRDY |
+---------------+---------------+---------------+---------------+

16554
Quad asynchronous serial interface controller with DMA support and 16-byte FIFOs.
PLCC68
+---------------+---------------+---------------+---------------+
| 10 /1DSR | 27 /2DCD | 44 /3DSR | 61 /4DCD |
| 11 /1CTS | 28 /2RI | 45 /3CTS | 62 /4RI |
| 12 /1DTR | 29 2RxD | 46 /3DTR | 63 4RxD |
| 13 VCC | 30 VCC | 47 VCC | 64 VCC |
| 14 /1RTS | 31 | 48 /3RTS | 65 /INTN |
| 15 1INT | 32 A2 | 49 3INT | 66 D0 |
| 16 /1CE | 33 A1 | 50 /3CE | 67 D1 |
| 17 1TxD&n