As the year comes to a close, it's worth a look back to consider what happened in the personal computer industry in 1987.

After two years of turmoil, the PC industry rebounded strongly in '87, and a raft of new hardware and software reached various stages of existence, from vaporware announcements to actual appearance on store shelves.

Among the notable developments:

IBM caused a major change in the industry with the announcement of its PS/2 personal computer line. After losing market share to vendors of compatibles like Compaq, Tandy and numerous others, IBM used a more proprietary approach for most of its lineup that, eight months after introduction, hasn't been cloned by any other manufacturer.

Manufacturers and attorneys alike say that cloning the PS/2 line may be a legally risky proposition, but most industry analysts expect to see PS/2-compatible machines from other vendors in 1988.

For end users, the switch to the technically superior 3.5-inch disk drive created logistical headaches as offices began to mix machines with differing disk formats.

Apple Computer added considerable heft to the Macintosh line with the introduction of the Macintosh SE and the Macintosh II, helping to establish the Macintosh as a serious business machine. Unlike IBM, Apple has had no competition in its direct area, as its highly proprietary technology makes legal cloning of an Apple II moderately difficult, and legal cloning of the Mac a near-impossibility.

Third-party vendors did make some inroads with compatible peripherals, like lower-cost laser printers for use with the Mac line.

In a move that rocked the software world and opened legal issues that have yet to be fully settled, Lotus Development Corp. sued Mosaic Software and Paperback Software, makers of spreadsheet programs similar in appearance to Lotus 1-2-3. The lawsuit brought on the now famed "look-and-feel" issue, which questions whether the appearance and the user interface of a software product falls under the laws governing copyright protection.

Speaking of software, there was no shortage of new software products in 1987.

Borland and Microsoft took on Lotus Development with new spreadsheet products aimed at eating into 1-2-3's dominance of the DOS-compatible spreadsheet world. Apple Computer introduced Hypertext, a new way of dealing with information in a data-base context, which was quickly imitated on the IBM-compatible side of the market.