Actually some Divici drawings show crude ram air designs, but actual R& D started in the mid to late 60s. The first "jumpable" ram air canopy was probably the Volplane, which I believe was manufactored by Pioneer.
In this time period the slider had yet to be invented so each manufactorer came up with their own unique reefing system to slow the openings.
The Volplane had a small hydraulic cylinder (about 8" long) sewn to the bottom canopy skin. A 1" steel ring was sewn to each "A" line near the canopy line attachments. The rings were stacked into a crab claw fitting on the hydraulic cylinder. The fitting was closed and the cylinder pumped up to pressure with a handle attached to the cylinder. The more the cylinder was pressurized, the slower the opening - in theory. The original versions of this thing had really long lines, about 30 feet.
Another early "square" was a Barish Sailwing. This was a real oddball in that it was a single surface (no cells) canopy. It had really tall ribs attached to the bottom of the single skin that would trap enough air to inflate the thing- sometimes. These were probably the most unreliable canopy ever made.
By the early 70s there were numerous makers of squares. Some were real companies and some were just cottage shops making copies of other companies designs.
In general, most all of the marketed mains from the early 70s until the ZP days, were bulky to pack, slow flying, docile and reliable.
A Canadian-born engineer named Domina Jalbert built the first ram-air canopies. Jalbert started building kites, then powered parachutes and finally ram-air parachutes. Much of Jalbert's research was funded by the Department of Defence and done at Notre Dame University under the supervision of Prof. Nicoladius (sp?).