The Macintosh 128K
In Figures 5 and 7 you have an overall look of the Macintosh 128K. The Macintosh 128K had a brightness adjustment button on its front panel, below the Apple logo.
The easiest way to detect that this is the original Macintosh from 1984 is that it only has “Macintosh” written on its back or “Macintosh 128K” on models manufactured after September of 1984. The Macintosh 512K had “512K” written on its back, and the successor to the 512K, the Macintosh Plus, had “Macintosh Plus” written on the front panel.
On the rear panel, the computer had a compartment for you to install a 4.5 V battery (known as TR133R, NEDA 1306A, 523, etc.) in charge of keeping the computer’s real time clock hardware working when the computer was turned off. Notice that this battery has the same physical size of a AA battery, but it is different (4.5 V vs. 1.5 V).
At the bottom part of the rear panel, the Macintosh 128K had a proprietary mouse port, a port for the installation of an external floppy disk drive, a serial port for a printer, a serial port for an external modem, and a 3.5 mm jack for an external speaker. The Macintosh 128K had an internal speaker as well.
It is interesting to note that while the serial port used on the PC used a male connector, the serial port used on the Macintosh used a female connector.