He procured a drive from his friends at HP and proposed to Bob Belleville that we figure out how to interface it to the Mac as soon as possible, while we negotiate a deal with Sony. George Crow, the analog engineer who designed the Mac's analog board, had come from HP prior to working at Apple and was sold on the superiority of the Sony drives. If we couldn't find a suitable replacement quickly enough, we'd have to slip the entire project indefinitely.įortunately, we were aware of Sony's new 3.5 inch drive that they started to ship in the spring of 1983 through Hewlett-Packard, their development partner. It looked like the Twiggy drive was never going to be reliable or cost effective enough for the Macintosh, but we were stuck without an alternative. We were using a single Twiggy drive as our floppy disk, and we didn't have a hard disk to fall back on. Meanwhile, the Mac team was beginning to panic. Finally, Lisas were shipped to customers in June 1983, even though there continued to be production and reliability problems with the disk drives. There were problems in a number of areas, but the biggest one was the low yield of the Twiggy drives, whose high error rate greatly limited production. Lisa was announced to great fanfare in January 1983, but it still wasn't ready to ship. Soon, the hard disk became mandatory, upping the minimum price of a Lisa by more than a thousand dollars. Besides, the Lisa operating system designers were used to working on systems that swapped memory from disk, which wasn't really feasible to pull off at floppy disk speeds. The Twiggy drive was also slower than expected, because of the high error rate as well as the way the variable motor speed trick increased seek times, since you had to wait for the speed change to stabilize. As the Twiggy designers encountered unexpected difficulties in achieving an acceptable error rate, Lisa came to rely on the hard drive instead. The Lisa also supported an optional, external hard drive through a built-in parallel port. Instead, the Lisa hardware designers (Paul Baker, Bob Paratore and others) solved the problem by including a little Apple II, with its own memory and microprocessor (but clocked twice as fast), inside the Lisa to control the Twiggy drives. Twiggy used a Woz-style disk controller, which created a problem for the Lisa designers, since that required exact timing from the microprocessor and therefore couldn't tolerate interrupts, which was perhaps OK for a simple system like the Apple II but was unacceptable for a more sophisticated system like Lisa. The Lisa was designed to include two built-in Twiggy drives, so it made sense for the Macintosh to use Twiggy as well. Twiggy was a fairly ambitious project, more than quadrupling the capacity of standard floppy disks by doubling the data rate (which required higher density media) and employing other innovative tricks like motor speed control, which slowed down the disk rotation speed on the outer tracks to cram more data on them. Woz's Apple II floppy disk design was way ahead of the rest of the industry, so Apple felt confident that it could continue to innovate to extend its lead. At Rod Holt's request, I had written some early diagnostics for Twiggy using an Apple II, but I felt lucky that they asked Rich Williams instead of me to transfer to the disk division as their software guy, since focusing exclusively on disks seemed pretty limiting. Both were intended to be used first by the Lisa project, and eventually across Apple's entire product line. In 1980, Apple reorganized again, splitting off a new "Disk Division" headed by John Vennard, responsible for developing a hard disk code-named "Pippin" and a next generation floppy disk code-named "Twiggy".
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