:OPENTD - Open DateStamper(tm) Time & Date file for Read/Write

  ENTER: A = 0 for Read, A = 0FFH for Write
  EXIT : A <> 0, Zero Flag Clear (NZ) if OK
	   A = 0, Zero Flag Set (Z) if Open Error
  USES : AF,BC,DE,HL
  REQUIREMENTS: You must select the drive before calling

 Usage: This DateStamper-specific routine is used to access
  large numbers of stamps, or where performance penalties in
  per-file stamp accesses are undesireable.  This routine Opens
  the TIME&DAT file in User 0 on the current drive.  If opened
  for writing, the R/O attribute is cleared.  The User Number
  is restored on exit.

CLOSTD - Close DateStamper(tm) Time & Date file

  ENTER: None
  EXIT : A <> 0, Zero Flag Clear (NZ) if OK
	   A = 0, Zero flag Set (Z) if Error
  USES : AF,BC,DE,HL

 Usage: This DateStamper-specific routine closes the TIME&DAT
  file in user 0 of current drive, and sets the R/O bit.  It is
  used in conjunction with OPENTD above.

FSTNXT - File search returning DateStamper(tm) Indices

  ENTER:  C - Search First (17) or Search Next (18) DOS command
	 DE - Points to FCB containg the target Filename.type
  EXIT :  A = Dir Index (0..3), Carry Flag Clear (NC) If Found
	    A indeterminate, Carry Flag Set (C) If NOT Found
	 DE - Contains random Sector number in !!!TIME&.DAT
	  B - Index into T&D sector (0..7)
  USES : AF,BC,DE,HL
  REQUIREMENTS: User must log Drive and User before calling

 Usage: This routine is used in DateStamper-specific systems to
  perform File searches and return indices into the Time & Date
  file.  Use this call for Function 17 and 18 Search calls in
  lieu of a direct call to the BDOS vector at location 5.

Example:
	EXT	FSTNXT		; Declare the routine
	...			; Log Drive/User & Set FCB
	LD	C,17		; Set for Search First command
	LD	DE,FCB		; ..addr FCB for desired name
	CALL	FSTNXT		; Search for the desired file
	JR	NC,FOUND	; ..jump if file found
	...			; Else do not found things

RWTD - Read or write to Time & Date file on current drive.

  ENTER:  A = 0 to Read, A = 0FFH to Write
	 DE - Contains Random Record to Read or Write
  EXIT : HL - Addresses the start of T&D sector Read/Written
	  A <> 0, Zero Flag Clear (NZ) if OK
	    A = 0, Zero Flag Set (Z) if Error
  USES : AF,BC,DE,HL and BDOS DMA Address

 Usage: DateStamper(tm)-specific routine normally used only for
  Directory list, Catalog or Archive programs where access to
  blocks of Date Stamps is desired.
  NOTE: You must reset DMA address after call if needed.

Example:
	EXT	RWTD		; Declare the routine
	...			; Log drive, Set DMA addr
	LD	DE,(RECNUM)	; Get T&D Rec # from FSTNXT or
				; ..specified Random rec number
	LD	A,MODE		; A=0 for read, A=FF for write
	CALL	RWTD		; Perform the action
	JR	NZ,RWOK		; ..jump if OK
	...			; Else perform error activity
 RWOK:	...			; Sector has been read/written
