A big selling point for the 128K was its : It measured 13.6 inches high by 9.6 inches wide by 10.9 inches deep and was much smaller than the typically wide desktop computers produced in the 1980s. The IBM PC/XT Model 286 released four years later in 1987 was 19.6 inches wide by 16.1 inches tall, according to . In fact, the original Mac's small footprint remains competitive by modern computer standards. Apple's current 21.5-inch all-in-one iMac, for example, measures 17.75 inches high by 20.8 inches wide by 7.4 inches deep.

Inside, the 128K had a lot of extra space set aside to make accommodate the CRT monitor.

Both the iPhone operating system and the 128K OS launched without multitasking. When the 128K came out you could do only one thing at a time on the machine. If you wanted to switch applications you had to insert a 3.5-inch floppy to load the new program. Apple sacrificed a lot of components typical in other computers, including RAM and storage space, to create a machine that was compact and affordable (by Apple standards).

You don't have to switch out disks on the iPhone, but until recently you could run only one application at a time on it. There were exceptions to that rule--for example, you could run the iPod and browse the Web simultaneously--but until , Apple didn't permit you to run more than one third-party app at a time. Despite Apple's recent changes, many observers have criticized the company for on the iPhone.