INT 12 - Back&Forth v1.62+ - API
AX = FFFEh
CX = FFFEh
BX = function
00h installation check
Return: AX = 0001h installed
else  not loaded
02h build program ID list
ES:DI -> buffer of at least 100 bytes, to be filled with words
Return: AX = number of programs defined
ES:DI buffer filled with AX words
03h switch to specified task (task need not be open yet)
DX = two-letter program ID
Return: AX = 0000h if task undefined
04h ???
05h ???
06h get version (undoc)
Return: AX = version * 100 (v1.71 = 00ABh)
07h ???
08h get open tasks (undoc)
ES:DI -> task info buffer (see below)
Return: AX = number of open tasks (max 20)
09h ???
Note:   Back & Forth is a task switcher by Progressive Solutions, Inc.

Format of task info buffer:
Offset  Size    Description
00h 21 BYTEs   ASCIZ task name
15h    BYTE    hotkey shift state (as for INT 16/AH=02h)
16h    WORD    hotkey scan code
18h    WORD    program ID

See also: 11FFFE

12FFFECXFFFE - Back&Forth v1.62+ - API