Format of PC-MOS/386 Current Directory Block:
Offset	Size	Description	)
 00h	BYTE	signature byte "H" if allocated from system memory pool
 01h	BYTE	header block ID, "C" = current directory block
 02h	WORD	length of block in paragraphs
 04h	WORD	segment address of next header block (0000h if last)
 06h	WORD	segment address of previous header block (0000h if first)
 08h	WORD	pointer to next TCB
 0Ah	WORD	pointer to previous TCB
 0Ch	WORD	pointer to associated TCB (if applicable)
 0Eh	WORD	reserved
---CDB---
 10h	BYTE	drive number
 11h	BYTE	???
 12h 64 BYTEs	directory name
 52h	WORD	first directory cluster (0000h = root)