I don't know much about the Apple II but I'm surprised that external circuitry is required to effectively count the number of frames. Isn't there already a way to count the number of frames without hardware hack on this computer?

Beyond that, an RTC without battery backup to maintain the time across reboots might not be extremely useful. Given the low precision I'd consider this more like a hardware timer than an RTC, but I'm probably splitting hairs now.

It's still a cool hack nonetheless, it's always refreshing to see how simple and straightforward it is to hack these old machines, both in hardware and software. Can you imagine doing something like that on a modern system? I mean, it's doable but it'll take more than three lines of assembly to get it to work correctly.