'70s and '80s you would advertise in computer magazines. At the bottom of each ad as a little number, and in the magazine was a tear-out postcard that went back

'70s and '80s you would advertise in computer magazines. At the bottom of each ad as a little number, and in the magazine was a tear-out postcard that went back to the magazine. The postcard was filled with little numbers; you would circle the number associated with and ad, and the company would send you information about their company, price lists, etc. The '70s and early '80s, it was CP/M, TRS-80, Apple ][ software. By the mid '80s and into the early '90s it was all one-person shops that were making custom UI controls for Windows 3.1. Tree and list controls were popular, plus some database connectors. By this time there were small companies making C++ libraries to make Windows programming easier, I remember Zinc and Zapp. They were wiped out when Visual C++ came out with Microsoft Foundation Classes.