September 10, 1984: Apple ships the Macintosh 512K, the first upgrade to the first-gen Macintosh 128K.
Coming less than eight months after the original Macintosh, the 512K Mac makes no sweeping changes to the computer’s form factor. Instead, the big upgrade is quadrupling the RAM. This leads Apple fans to refer to the computer as the “Fat Mac.”
Macintosh 512K appeals to more than early adopters
Apple had good reason to rush the 512K Mac to market, even though the first Mac actually exceeded Steve Jobs’ early sales forecasts. Apple sold 72,000 Macintosh 128K models in the first 100 days, rather than the expected 50,000. However, these buyers proved different from longer-term customers.
Read more at CultofMac.com