Format of HP 95LX file state record:
Offset	Size	Description	)
 00h	WORD	DOS file handle
 02h	WORD	state flags (see #03288)
 04h	DWORD	current DOS physical file offset (FFFFFFFFh if unknown)
 08h	DWORD	DOS file offset of start of buffer
 0Ch	DWORD	effective file offset as seen by caller
 10h	WORD	number of bytes in file buffer
---buffered I/O only---
 12h 512 BYTEs	file buffer