I looked it up.
https://en.wikipedia.org/wiki/Harvard_Graphics
1986 is when we bought the film recorder. I had to do a lot of digging to figure out the only way to get Harvard Graphics files to work with our film recorder was to set up a special boot disk. It was a 5.25 inch floppy we gave to customers. They built the files they way they wanted and then re-booted from my floppy and it would allow them to make SCODL files. Those SCODL files were what the film recorder required to image the files. If they did not boot from the floppy the drivers needed in the config.sys and autoexec.bat would not load. If they loaded those drivers all the time it messed with all sorts of other systems on the computer. Back when most computers had just one meg of memory and every K of ram was needed only the basic drivers were loaded.
It is almost hard to believe we used computers with 640K or a full megabyte of ram and a 32 MB hard drive was large. My computer had two monitors in 1986. The main system monitor was monochrome. Black background and amber text. The other monitor did a full color of the slide preview. We paid 5 grand for a IBM AT 6 MHz with a 32 MB hard drive and 1 meg of RAM.