In this context:

• CPU is logical component («idea» of instruction performing machine)
• microprocessor is physical chip with actual CPU

Terms:

• Microprocessor — physical chip with CPU
• Microcontroller — physical chip with CPU, memory and IO-interface
• FPGA
• ASIC

CPU (Central Processing Unit) — “brain” of a computer

• ALU (Arythmetic Logic Unit) — CPU component used for calculations
• Instructions decoder — component that transforms opcodes to CPU instructions
• Opcode (Operation Code) — enumerated value (like 11100011 00001010) that specifies operation to be performed
• Clock — component that synchronizes all CPU components

Memory:

• Registers — fast and small memory directly integrated into CPU
• Volatile memory — one that requires power to store data
• Non-volatile memory — persistent data storage
• Cache — small fast memory (slower than registers, faster than RAM) that stores copies of frequently used data from main memory (which is slow to access)

Input/Output — communication between CPU and external peripherals to send and receive data

ISA and real-life architectures:

• x86: 80+ ISA for 8086, 1000+ modern
• x86 / AMD = same ISA, different hardware
• RISC-V: core 47, additional 100+
• ARM

Firmware — software embeded into hardware.

BIOS:

• microcode — software layer inside cpu, stored and loaded from bios
• BIOS/UEFI:
  • firmware/software that runs on main CPU
  • CPU starts on hardwired «reset vector» that points to BIOS location
  • BIOS loads microcode into CPU
  • BIOS is stored in EEPROM (non-volatile memory)
• CMOS — stores some BIOS info (date-time, boot order), volatile memory depending on battery

Levels:

• machine code (11001100 00101011 …)
• object code (machine code + linking info)
• assembly (specific for every CPU or at least CPU Architecture)
• C/C++ and higher-level languages