The comments in the programs for the Keil compiler are in Chinese so I ran them through a translator and then added them to the Github repo as parallel files. The translator inserted spaces in some places so they will provoke syntax errors if you try to compile them, so don't do that. They are only for reading the comments. Some are relevant such as notes that a jumper must be disconnected for a particular experiment. For example the port driving the LEDs is also used for input in some experiments so the LEDs need to be disconnected for those. Some comments explain the calculations behind time-critical delays.
I will transfer the relevant comments to the SDCC versions which I'll be testing soon.
I also found a higher resolution version of the schematic which should be easier to read.