Is a CMOS IC chip ROM or RAM?

Answer 1

It is neither or could be either.

Specifically CMOS is a digital logic circuit implementation technology. It stands for Complementary Metal Oxide Semiconductor, which means:

1. Complementary - uses both N channel and P channel Metal Oxide Field Effect Transistors (MOSFETs), not just one or the other type;
2. Metal - uses metal gate FETs, not polysilicon gate FETs (see above);
3. Oxide - uses silicon dioxide insulated gate FETs, not PN junction gate FETs aka JFETs (see above);
4. Semiconductor - just what it means and to make a good sounding pronounceable acronym.

CMOS technology can be used to implement ANY kind of digital logic circuit: logic gates, flipflops, RAM, ROM, etc.

One of the advantages of CMOS technology over other digital logic circuit implementation technologies (e.g. RTL, DTL, TTL, HTL, ECL, NMOS, PMOS, IIL) is that power consumption is directly proportional to switching rate, with it approaching zero when the devices a just sitting idle (a leakage current in the microampere range does continue to be drawn). This makes CMOS an ideal technology for implementing a RAM device for storing configuration parameters while the machine is turned off, this so called CMOS RAM is able to be kept powered all the time so it can retain the parameter data by just a tiny "coin cell" battery. This offers both the advantages of RAM (modifiability) and ROM (nonvolatility).

Most modern microprocessor, support, RAM, and ROM IC chips are now implemented with CMOS technology.