DOS Fn 4b05H: Set Execution State
Expects: AX 4b05H
DS:DX address of an ExecStateRec containing execution state info
Info: This function sets up DOS for executing a loaded program.
Specifically, it prepares DOS to correctly handle calls to Fn 30H
(get DOS version), as set up by the DOS Setver program.
DS:DX points to a block of memory prepared as an ExecStateRec that has
been filled with the information needed.
Notes: ■ This function is required by programs which intercept (and
replace) fn 4B00H (exec).
■ After return, the caller should immediately begin executing the
program, specifically avoiding any DOS or BIOS fn calls.
■ When DOS is installed in the HMA▲, this function turns off the
A20 line (making the HMA inaccessible). DOS normally turns A20
on and leaves it on while executing other system functions.
See Also: Fn 4b00H (execute program)
Fn 4b01H (load program)
Fn 4b03H (load overlay)
Process Control Functions
Program Startup & Exit