Mike Riddle's Prehistoric AutoCAD

Evan Yares writes: "This is a photo of the INTERACT CAD system, circa 1978. The hardware is an S-100 computer with dual 8" floppy drives, and a 640x480 pixel graphics board.  Input is through a Houston Instruments digitizer and a Televideo terminal. I don't know what brand plotter it's using, but is using a Rapidograph pen, with either an HP or HI adapter.

INTERACT was the first CAD system to run on mainstream microcomputer hardware. (Other systems ran on mainframes or minicomputers.) Its first commercial customer was Atlantic Richfield. I understand they used it to plan deep dives for offshore drilling rigs.

INTERACT was written by Mike Riddle. He had previously worked on an expensive ComputerVision CADDS3 system, and figured he could do better. He wrote INTERACT in his spare time, starting in 1977. He was somewhat slowed down by the state of hardware at the time -- he had to write the program in pieces, and assemble it as larger memory boards became available. Ultimately, he decided he needed a processor that could support hardware multiply. Marinchip Systems, owned by John Walker and Dan Drake, made an S-100 main board with a TI TMS-9900 processor that fit the bill.

In 1981, Riddle, Walker, Drake, and about a dozen other people co-founded Autodesk. Interact was rewritten in C to run on the new IBM PC, and was rechristened AutoCAD. It has since grown to be the most popular CAD program in history." [thanks for the flashback, Evan!]

Mike Riddle & the Story of Interact [DigiBarn]