How to send keyboard input to dos application running in window mode in Windows98

My question is about very antique techologies. I have a task to automate old DOS software (spectrometric) that is running in Windows mode in Windows 98. I made two different solution hovewer both of them doesn't work with DOS application:

First Solution
- Making DOS Application active
- Sending input via SendInput function, like this:

    void MossbauerLab::Sm2201::SaveManager::AutoSaveManager::sendKeysViaInput(const std::vector<DWORD>& keys, int keyPause)
    {
        std::vector<DWORD>::const_iterator it;
        INPUT keyBoardInput;
        keyBoardInput.type = INPUT_KEYBOARD;
        keyBoardInput.ki.wScan = 0;
        keyBoardInput.ki.time = 0;
        keyBoardInput.ki.dwExtraInfo = 0;

        for(it = keys.begin(); it != keys.end(); it++)
        {
            keyBoardInput.ki.wVk = (*it);
            keyBoardInput.ki.dwFlags = 0;   // key down
            SendInput(1, &keyBoardInput, sizeof(INPUT));
            Sleep(keyPause);
            keyBoardInput.ki.dwFlags = 2;   // key up
            SendInput(1, &keyBoardInput, sizeof(INPUT));
            Sleep(keyPause);
        }
    }

Generate key press via i8042 keyboard controllers: write to keyboard buffer command using D2 command, like this (KEYBOARD_CMD_REG - 0x64, KEYBOARD_DATA_REG - 0x60):

    void MossbauerLab::Sm2201::SaveManager::AutoSaveManager::sendKeysViaKeyboardController(const std::vector<BYTE>& scanCodes, int keyPause)
    {
        std::vector<BYTE>::const_iterator it;
        for(it = scanCodes.begin(); it != scanCodes.end(); it++)
        {
            // wait untill buffer is empty
            int status = 0;
            int result = 0;
            do
            {
                status = _inp(0x64);
                // std::cout <<"Keyboard status: "<< status << std::endl;
                Sleep(10);
            }
            while (status & 1);

            // send scan code for key down
            _outp(KEYBOARD_CMD_REG, 0xD2);
            _outp(KEYBOARD_DATA_REG, (*it));
            result = _inp(KEYBOARD_DATA_REG);
            std::cout <<"Keyboard command result for KEY DOWN: "<< result << std::endl;
            // send scan code for key up
            BYTE keyUpCode = (*it) | 128;
            Sleep(keyPause);
            _outp(KEYBOARD_CMD_REG, 0xD2);
            _outp(KEYBOARD_DATA_REG, keyUpCode);
            result = _inp(KEYBOARD_DATA_REG);
            std::cout <<"Keyboard command result for KEY UP: "<< result << std::endl;
        }
    }

I tested both of these solutions with standard Notepad window (notepad.exe) and both of them works fine, but i can't get it work with DOS application.

My Code where i generate keyboard input (and whole project): https://github.com/MossbauerLab/Sm2201Autosave/blob/master/MossbauerLab.Sm2201.ExtSaveUtility/src/saveManager/autoSaveManager.cpp

Could you please help me to solve this solution.

Solution

First of all i want to thank all who interesting this post, all of you gave me some useful info and i finally made what i wanted.

About how it was implemented: i've created VXD driver (it is my proprietary driver and i can't post it code here because i am planning to use it for commercial projects). But the main goal of this comment - YES, it is possible to simulate KEYBOARD INPUT for DOS application running in Windows 98 in window mode. Part of my solution that i could post is on github: https://github.com/MossbauerLab/Sm2201Autosave/blob/master/MossbauerLab.Sm2201.ExtSaveUtility/src/saveManager/autoSaveManager.cpp

Here i am using vXd accessor class: (https://github.com/MossbauerLab/Sm2201Autosave/blob/master/MossbauerLab.Sm2201.ExtSaveUtility/src/utils/windows/vxdAccessor.cpp)

Main idea - interact with driver using W32_DEVICEIOCONTROL driver message handler and DeviceIoControl function and passing struct that have 1 byte align using CTL (define in my driver) CODES: i did not used CTL_CODE macro. This Github project is almost ready ~95% (at present time i just have to manual select window to send by activate it with mouse click and check proper memory free).