IBM manual ThinkPad X20, X21, X22, X23, X24

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 12.1-inch, 16M colors SVGA
	(800⋅600 resolution) TFT color LCD
	v 12.1-inch, 16M colors XGA
	(1024⋅768 resolution) TFT color LCD
	X22, X23, X24
	v 12.1-inch, 16M colors XGA
	(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, Line-in,
	Headphone, Docking, 1394 (Some
	Models)
	X22, X23, X24
	USB, RJ11, RJ45, VGA, Mic, IrDA,
	Line-in, Headphone, Docking, 1394
	(Some Models)
Internal modem	X20, X21, X22, X23, X24
	v V.90 D/F

Chapter 3. ThinkPad X20, X21, X22, X23, X24 43