PowerBook 540

The Apple Macintosh PowerBook 540 features a 33 MHz 68LC040 processor, 8 MB or 12 MB of RAM, and a 240 MB hard drive in a sleek portable case with a 9.5" grayscale active-matrix display.

The PowerBook 540 is similar to the PowerBook 520, but has a faster processor and a higher quality 6-bit and active-matrix display.

Source https://everymac.com/systems/apple/powerbook/specs/mac_powerbook540.html