Int 21H, AH=63H, AL=00H

2.25, 3.2 and higher

GET LEAD BYTE TABLE ADDRESS

      AX = 6300h

CF clear if successful
DS:SI -> lead byte table (see #01746)
CF set on error
AX = error code (01h) (see #01680 at AH=59h/BX=0000h)

note: NO CF flag used in some versions
AL = error code
  00h successful all other registers except CS:IP and SS:SP destroyed
  FFh not supported
 

Does not preserve any registers other than SS:SP.
Probably identical to AH=63h/AL=00h for DOS 2.25. The US version of MS-DOS 3.30 treats this as an unused function, setting AL=00h and returning immediately, WITHOUT setting DS:SI; only the Far East versions of MS-DOS 3.2 and 3.3 supported this call. The US version of DOS 4.0+ accepts this function, but returns an empty list. IBM DOS 6.1 SYS.COM assumes that CF is set on error

Format of double-byte character set lead byte table entry:

Offset  Size    Description     (Table 01746)
00h  2 BYTEs   low/high ends of a range of leading byte of double-byte chars
02h  2 BYTEs   low/high ends of a range of leading byte of double-byte chars.
...
N   2 BYTEs   00h,00h end flag

AX=6301h - AH=07h - AH=08h - AH=0Bh

Text based on Ralf Brown Interrupt List Release 61