The SD card interface uses a 65C22 chip ("VIA") for the I/O between the computer and the SD card, but that chip is also available to the programmer for other purposes. For example keeping track of passing time, something that's not possible on the naked Apple-1. So I wrote a demo ("VIACLOCK") where a timer is set to generate an interrupt at the rate of one second (corresponding to 15996 CPU clock cycles). The routine that responds to the interrupt keeps account of passing seconds and draws a digital clock in BIG fonts on the screen.
See the video: https://www.youtube.com/watch?v=yWrxlwocEXs
The demo is written in C and its source code is available here: https://github.com/.../blob/main/demos/viatimer/viaclock.c
Curiosity: it can recognize the Replica-1, in which case it takes into account the missing RAM refresh cycles.
Note: if you try it on your SD card interface, don't forget to short the "interrupt" jumper on the interface, that's how the INT signal is delivered to the 6502 CPU.
SD card info: https://p-l4b.github.io/sdcard/