Martin Webb, who developed the OutRun port for Commodore back in the 80's has been chronicling that journey on his professional page and it been a fascinating read. Enjoy!

I made a thing, it shows checksums when you input basic lines. It handles 10 different algorithms (only 6 in the video), and you can change it using a single peek (shown in the help, which you can also access with SYS 50000.

The supported modes are:

1. F64Summer (2018, Felix Palmen)
2. 64'er Checksummer V1/V2 (V1 October 1984, Frank Lonczewski)
3. 64'er Checksummer V3
4. COMPUTE! Automatic Proofreader V1 (1983/84), Charles Brannon
5. COMPUTE! New Automatic Proofreader V2/V3 (1986/2026), Philip I. Nelson
6. AHOY! Bug Repellent V2 (1984)
7. AHOY! Bug Repellent V3 (1987)
8. HCM (Home Computer Magazine) Bug-Out V5.5 (1985)
9. RUN Checksum V2 (1988), Bob Kodadek

+ 0 which is just a tiny one I added as a default.

I put it on a .d64 here: tg-check.d64

Source is on GitHub.

Thankful for any bug reports etc.