Int 21/AX=5758h

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Headroom - API

AX = 5758h
BL = function
00h ???
01h get Headroom location

Return:
CF clear if installed AX = PSP segment of Headroom TSR BX = paragraphs of memory used by Headroom CF set if not (normal DOS return)

Note: This function is also used as an installation check 02h get INT 21 handler

Return:
CF clear ES:BX -> Headroom's INT 21 handler

Note: Also sets unknown flag 03h launch application??? DS:SI -> 233-byte application record

Return:
??? 04h ??? ???

Return:
CF clear 05h get swap directory

Return:
CF clear DX:AX -> ASCIZ swap directory name 06h ??? DX = ???

Return:
CF clear 07h ??? 08h ??? 09h get current application

Return:
BX = application number 0Ah ??? DX = application number DS:SI = ???

Return:
??? 0Bh ??? 0Ch ??? DX = application number ???

Return:
??? 0Dh ??? DX = application number ???

Return:
??? 0Eh get ???

Return:
CF clear AX = ??? 0Fh set ??? flag 10h clear ??? flag 11h find application by name DS:SI -> ASCIZ application name

Return:
CF clear AX = application number or FFFFh if not loaded 12h ??? DX = application number

Return:
CF clear ??? 13h ???

Return:
CF clear 14h ??? same as function 13h 15h set ??? DX = ??? 16h get ???

Return:
AX = ??? set by function 15h 17h get ???

Return:
BX = ??? CX = ??? (may be pointer in BX:CX)

18h BUG:
Branches incorrectly due to fencepost error

Program: Headroom is a TSR/task switcher by Helix Software

See Also: AX=4C57h - AX=5757h - INT 2F/AX=5758h

Category: Uncatagorized - Int 21h - H

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