Intended as a replacement for the Macintosh Portable, the 140 series was identical to the 170, though it compromised a number of the high-end model's features to make it a more affordable mid-range option.

Internally, in addition to a slower 16 MHz processor, the 140 also lacked a Floating Point Unit (FPU) and could not be upgraded.

The 140 was introduced with System 7.0.1, specifically to support new power management and other unique hardware features.

The 145 also introduced a new feature for the battery-conscious: users would be able to configure the 145 to sleep or completely shut down whenever the clamshell unit was closed.

Unlike previous Mac models but like the Performas, the 145B did not ship with a full set of system disks.

The package also included two utilities that provide basic backup and restore functions.