Ron provided an assembler and all the available assembly listings. People went to museums and hand entered the assembly code and verified it by assembling the code and running it through Ron's simulator. That was a HUGE effort and HUGE thanks to everyone involved in that effort.
All I did was extend the assembler by adding an option to output the machine code in a Motorola S-record format. I use this output file as an input into my version of the simulator and as input into my ROM burner to burn the code into an EPROM for the hardware I am developing.
My modifications to Ron's assembler can be found on my GitHub site at https://github.com/bglasford1 Under the AGCBlockIIComputer project there is a YUL directory that contains my modifications. The original assembler was named YUL because they had a Christmas deadline. You can recreate the assembler I am using by first downloading Ron's yaYUL code and then adding my modifications to it.