please can u more deitels about that
This is really not the place to ask for help about emulation.
Nonetheless, something like DosBox can be found
here and it has it's own wiki
here.
In case you do not fancy dosbox or wish to run an emulator on another host plaform (unsupported by dosbox) then just do a google search on "list of msdos emulators", take a pick and read the corresponding documentation.
The basics are the same.
1 - Install the emulator on your machine
2 - configure your emulator
3 - install ms dos or equivalent
4 - install your old turbo pascal program
5 - run your old Pascal program just as you would have done on a real ms-dos machine
With regards to virtualization software, you could follow a guide such as listed
here.
If you are able to run your old software this way without any issues then you just bought yourself time.
You could then use that time to start doing an inventory on what your old program uses, e.g. what kind of screens, windows, editboxes etc are used and which match those from Lazarus.
You said that your program has more than 100000 lines of code but, in turbo vision you almost had to modify every existing object manually to accommodate your needs.
Even though this is also true for the 'matching' components in Lazarus, most of the component in Lazarus are much more flexible and offer most functionality out of the box (or with little programming effort).
However, porting your old turbo vision application over to Lazarus is (and always will be) manual labour. There is no automated process that is able to help you there.
In case you have your 'working' code separated from your (Turbo Vision) gui then it is often quite possible that you are able to copy parts of your code. In case you have a tight integration with Turbo Vvision's GUI then you have a long road ahead of you.
Point being that there can't be anything said unless having seen the actual code. You really need to analyze and make an inventory about what would need to be ported or not.
In case you do not have any experience with Lazarus then i strongly suggest to start with playing with Lazarus instead of trying to port your code right away.
Only if you know what Lazarus can do _then_ you are able to tell what is required to port your old Turbo Vision application.
just 2 cents.