Rebuilding a Visual Basic 6 or Delphi program

The usual situation

• The program only starts on a PC running Windows 7 or XP, kept on in a corner of the office for that reason alone.
• On Windows 11 it needs a runtime or a library installed by hand, and after every update you hope it starts.
• Whoever wrote it has closed their business or stopped answering.
• The printouts still come out, but nobody knows how to change them.
• The data lives on that PC, and the backup is a USB stick when someone remembers.

What it becomes

A custom web app in PHP 8 with MySQL or MariaDB, following the same rules as the old program. It opens in any browser, on any PC, and several people use it at once. Backups run every day on the server, with no USB sticks involved.

If the old program talked to printers, scales or barcode readers, that part can stay in a desktop app that works together with the web app.

How I rebuild it

1. I open the old program and write down what it really does, including the rules nobody remembers: the discount that only applies to some customers, the document number that restarts in January. The analysis is free.
2. I read the data where it sits and write the script that imports it. It can run again without creating duplicates.
3. I build the new app in stages, on a test address. Meanwhile the old program stays on and you work as usual.
4. On switch-over day I run the import again, with that morning's data.

I have worked on VB6 and Delphi software before, and I used the same method for my own CRM, which replaced a spreadsheet with 18 sheets.

Better before it stops

While the old program still works, you can compare results: same invoice, same total, in the old one and the new one. Once it has stopped, the rules have to be pieced together from the data and from what people remember, and that takes longer. A spare PC with a copy of the disk buys a few months, and in the meantime the new app gets built.

Frequently asked questions

We don't have the source code. Can it still be rebuilt?

Yes. We start from the program in use and its data: I look at the windows, at what each button does and at what ends up in the database. With the code it goes faster, because the hidden rules can be read there.

Where does a program like this keep its data?

Often in an Access database (.mdb), sometimes in its own files or in SQL Server. I read .mdb files without needing Access; other formats we look at during the analysis.

Can't we just move it to a new PC?

Sometimes that works, for a while. Every Windows update is still a risk, and the day the program won't start, the work stops with it. Rebuilding it while it still runs lets you choose the timing.

The program drives a label printer or a scale. Can that work from a browser?

It depends on the device. If the browser can't reach it, a small desktop program talks to the device and works alongside the web app, on the same data.

Read more

• The service: Rebuilding old software
• More pages like this: Moving off spreadsheets and old software