Format of PCMCIA Socket Characteristics table:
Offset	Size	Description	)
 00h	WORD	supported card types (see #00683)
 02h	WORD	steerable IRQ levels (bit 0 = IRQ0 to bit 15 = IRQ15)
 04h	WORD	additional steerable IRQ levels
		bit 0: NMI
		bit 1: I/O check
		bit 2: bus error
		bit 3: vendor-unique
		bits 4-7 reserved (0)