| Memory (standard) | X20, X21 | 
| 
 | v 64 MB (on the system board) | 
| 
 | v 128 MB (on the system board) | 
| 
 | X22, X23, X24 | 
| 
 | v 128 MB (on the system board) | 
| 
 | v 256 MB (on the system board plus | 
| 
 | 128 MB DIMM) | 
| 
 | 
 | 
| Memory (optional) | X20, X21 | 
| 
 | v 64 MB, 128 MB, or 256 MB SDRAM | 
| 
 | card (maximum of 320/384 MB) | 
| 
 | X22, X23, X24 | 
| 
 | v 64 MB, 128 MB, 256 MB or 512 MB | 
| 
 | SDRAM card (maximum of 640 MB) | 
| 
 | 
 | 
| CMOS RAM | X20, X21 | 
| 
 | v 114 bytes +4 Kbytes | 
| 
 | X22, X23, X24 | 
| 
 | v 256bytes | 
| Display | X20, X21 | 
| 
 | v  | 
| 
 | (800⋅600 resolution) TFT color LCD | 
| 
 | v  | 
| 
 | (1024⋅768 resolution) TFT color LCD | 
| 
 | X22, X23, X24 | 
| 
 | v  | 
| 
 | (1024⋅768 resolution) TFT color LCD | 
| 
 | 
 | 
| Hard disk drive | X20, X21 | 
| 
 | v 10GB, 20GB | 
| 
 | X22 | 
| 
 | 10GB, 15GB, 20GB, 30GB | 
| 
 | X23, X24 | 
| 
 | 20GB, 30GB | 
| 
 | 
 | 
| I/O port | X20, X21 | 
| 
 | v USB, RJ11, RJ45, VGA, Mic,  | 
| 
 | Headphone, Docking, 1394 (Some | 
| 
 | Models) | 
| 
 | X22, X23, X24 | 
| 
 | USB, RJ11, RJ45, VGA, Mic, IrDA, | 
| 
 | |
| 
 | (Some Models) | 
| 
 | 
 | 
| Internal modem | X20, X21, X22, X23, X24 | 
| 
 | v V.90 D/F | 
| 
 | 
 | 
Chapter 3. ThinkPad X20, X21, X22, X23, X24 43
