With Wednesday’s expected unveiling of the Apple tablet, the tech world is bracing for a device that could revolutionize everything from mobile computing to the newspaper industry. But what if the tablet doesn’t live up to expectations?

While Apple is known for its golden touch, the company has had its share of flops. The five products below represent some of Apple’s biggest disappointments; but theyNewton also provide important lessons that can be found in its smash hits.

Newton: First released in 1993, the Newton represented one of the first attempts at a mass-market, touchscreen-based handheld computer. But the brick-sized Message Pad family of devices that ran the Newton operating system were too big and, at $700-plus, too pricey. And the mixed results of the initial version of the handwriting recognition made Newtons an easy target for criticism.

While some cite the Newton as a progenitor to the iPhone and the expected tablet, it’s notable that the Newton was developed while Apple CEO Steve Jobs was in exile. Within two years of Jobs’ return in 1996, the Newton was cast overboard.

Lisa: Before there were Macs or Windows PCs, there was Apple’s Lisa, one of the first commercially available PCs to feature a graphical user interface. Introduced in 1983, the PC featured a 5Mhz Motorola 68000 CPU, 1MB of RAM and two 5.25 inch floppy drives. At $10,000, the Lisa was expensive even for business customers (Wikipedia cites NASA as one of the biggest customers) and its performance was deemed somewhat sluggish, according to some accounts. The release of the less expensive Macintosh PCs in 1994 1984 made it hard to justify purchasing a Lisa, and Apple killed the product in 1986.