The MC6850P and 9 pin connector suggest that you have a serial card. A slow serial card.
Iron merchant == scrap merchant. Traditionally, scrap merchants picked up old iron, copper, brass and lead waste from homes and factories. Today, scrappers pick up old computers as well -- for resale, parts salvage (valuable chips) and eventually metal recovery. You are lucky to have someone who does not immediately trash old computers: have you talked to them about the sources of their old computer junk? There might be a business opportunity.
Pardon, the intrusion, but where does motion live? It makes a difference.