I am currently reading Digital Computer Electronics, and on page 4 of the book (page 7 of the PDF), I am confused by this diagram:
The diagram shows that the transistors with no (or almost no) current being supplied to the base have their outputs on.
The authors even describe the leftmost transistors as being cut off, despite showing 5V output:
The transistors on the left are cut off because the input base voltages are 0 V. The dark shading symbolizes the cutoff condition. The two transistors on the right have base drives of 5 V. The transistors operate at either saturation or cutoff. A base voltage of 0 V forces each transistor to cut off, while a base voltage of 5 V drives it into saturation.
I think this may be a difference between NPN and PNP transistors, but I'm not totally sure because of the way the authors described the left ones as being cut off despite showing 5V.
Any help would be appreciated. Thanks!