While Heath/Zenith's computer business was successful, the growing popularity of home computers as a hobby hurt the company because many customers began writing computer programs instead of assembling Heathkits. Also, while their assembly was still an interesting and educational hobby, kits were no longer less expensive than preassembled products; "BYTE" reported in 1984 that the kit version of the Z-150 IBM PC compatible cost $100 more than the preassembled computer from some dealers, but needed about 20 hours and soldering skills to assemble. The continuation of the integration trend (printed circuit boards, integrated circuits, etc.), and mass production of electronics (especially computer manufacturing overseas and plug-in modules) eroded the basic Heathkit business model. Assembling a kit might still be fun, but it could no longer save much money. The switch to surface mount components and LSI ICs finally made it impossible for the home assembler to construct an electronic device for significantly less money than assembly line factory products. As sales of its kits dwindled during the decade, Heath relied on its training materials and a new venture in home automation and lighting products to stay afloat. When Zenith eventually sold ZDS to Groupe Bull in 1989, Heathkit was included in the deal.