a search for hwj1306b found this link

https://damogranlabs.com/wp-content/...-cnc-guide.pdf

the breakout board is another variant of the chinese boards used in 6040 cnc machines and sold on ebay or amazon etc

going by the photo on page 13 of the damogranlabs guide
nothing remarkable - just another Mach3 or linux CNC BOB

I guess the 12 printer port outputs are buffered by two 74hc244 or 74hc245 IC's

four of the five inputs for your limit switches & touch probe are isolated by opto-isolators (pc817 ?)
the E-stop switch being connected directly to the printer port

John