Uncommon original Apple Computer ‘Engineering Release’ schematic of the electronic circuitry used to control the Twiggy floppy disk drive in the original Apple Lisa computer. The sheet, one page, 17 x 11, entitled “Schematic, Digital Board, Twiggy,” dated December 1982, provides technical information about how the drive interfaces with the Lisa's main system and how it manages the reading and writing of data on the disks. Marked “Apple Computer Confidential,” the sheet is identified as Drawing No. 050-5002-F and bears a 1983 revision memo to the upper right. In fine condition. A fascinating technical document related to the infamous Twiggy drives of the original Lisa 1. When Apple released the Lisa 2, they replaced the Twiggy drives with a single 3.5-inch Sony drive and an optional external hard drive, vastly improving the system's reliability and performance.
