Central processing unitA central processing unit (CPU)—also called a central processor or main processor—is the most important processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, logic, controlling, and input/output (I/O) operations. This role contrasts with that of external components, such as main memory and I/O circuitry, and specialized coprocessors such as graphics processing units (GPUs). The form, design, and implementation of CPUs have changed over time, but their fundamental operation remains almost unchanged.
8-bit computingIn computer architecture, 8-bit integers or other data units are those that are 8 bits wide (1 octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data buses of that size. Memory addresses (and thus address buses) for 8-bit CPUs are generally larger than 8-bit, usually 16-bit. 8-bit microcomputers are microcomputers that use 8-bit microprocessors.
4-bit computing4-bit computing is the use of computer architectures in which integers and other data units are 4 bits wide. 4-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data buses of that size. Memory addresses (and thus address buses) for 4-bit CPUs are generally much larger than 4-bit (since only 16 memory locations would be very restrictive), such as 12-bit or more, while they could in theory be 8-bit. A group of four bits is also called a nibble and has 24 = 16 possible values.
Compressed instruction setA compressed instruction set, or simply compressed instructions, are a variation on a microprocessor's instruction set architecture (ISA) that allows instructions to be represented in a more compact format. In most real-world examples, compressed instructions are 16 bits long in a processor that would otherwise use 32-bit instructions. The 16-bit ISA is a subset of the full 32-bit ISA, not a separate instruction set. The smaller format requires some tradeoffs: generally, there are fewer instructions available, and fewer processor registers can be used.
One-instruction set computerA one-instruction set computer (OISC), sometimes referred to as an ultimate reduced instruction set computer (URISC), is an abstract machine that uses only one instruction - obviating the need for a machine language opcode. With a judicious choice for the single instruction and given infinite resources, an OISC is capable of being a universal computer in the same manner as traditional computers that have multiple instructions. OISCs have been recommended as aids in teaching computer architecture and have been used as computational models in structural computing research.
Control storeA control store is the part of a CPU's control unit that stores the CPU's microprogram. It is usually accessed by a microsequencer. A control store implementation whose contents are unalterable is known as a Read Only Memory (ROM) or Read Only Storage (ROS); one whose contents are alterable is known as a Writable Control Store (WCS). Early control stores were implemented as a diode-array accessed via address decoders, a form of read-only memory. This tradition dates back to the program timing matrix on the MIT Whirlwind, first described in 1947.
Zilog Z80The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples were delivered in March 1976, and it was officially introduced on the market in July 1976. With the revenue from the Z80, the company built its own chip factories and grew to over a thousand employees over the following two years.
Broadwell (microarchitecture)Broadwell is the fifth generation of the Intel Core Processor. It is Intel's codename for the 14 nanometer die shrink of its Haswell microarchitecture. It is a "tick" in Intel's tick–tock principle as the next step in semiconductor fabrication. Like some of the previous tick-tock iterations, Broadwell did not completely replace the full range of CPUs from the previous microarchitecture (Haswell), as there were no low-end desktop CPUs based on Broadwell.
Intel AtomIntel Atom is a line of IA-32 and x86-64 instruction set ultra-low-voltage processors by Intel Corporation designed to reduce electric consumption and power dissipation in comparison with ordinary processors of the Intel Core series. Atom is mainly used in netbooks, nettops, embedded applications ranging from health care to advanced robotics, mobile Internet devices (MIDs) and phones. The line was originally designed in 45 nm complementary metal–oxide–semiconductor (CMOS) technology and subsequent models, codenamed Cedar, used a 32 nm process.
ItaniumItanium (aɪˈteɪniəm ) is a discontinued family of 64-bit Intel microprocessors that implement the Intel Itanium architecture (formerly called IA-64). The Itanium architecture originated at Hewlett-Packard (HP), and was later jointly developed by HP and Intel. Launched in June 2001, Intel initially marketed the processors for enterprise servers and high-performance computing systems. In the concept phase, engineers said "we could run circles around PowerPC, that we could kill the x86.
