HOME
The Info List - 8-bit



--- Advertisement ---


In computer architecture , 8-BIT integers , memory addresses , or other data units are those that are 8 bits (1 octet ) wide. Also, 8-bit CPU and ALU architectures are those that are based on registers , address buses , or data buses of that size. 8-BIT is also a generation of microcomputers in which 8-bit microprocessors were the norm.

The IBM System/360 introduced byte-addressable memory with 8-bit bytes, as opposed to bit-addressable or decimal digit-addressable or word-addressable memory, although its general purpose registers were 32 bits wide, and addresses were contained in the lower 24 bits of those addresses. Different models of System/360 had different internal data path widths; the IBM System/360 Model 30 (1965) implemented the 32-bit System/360 architecture, but had an 8 bit native path width, and performed 32-bit arithmetic 8 bits at a time.

The first widely adopted 8-bit microprocessor was the Intel 8080 , being used in many hobbyist computers of the late 1970s and early 1980s, often running the CP/M
CP/M
operating system ; it had 8-bit data words and 16-bit addresses. The Zilog Z80 (compatible with the 8080) and the Motorola 6800
Motorola 6800
were also used in similar computers. The Z80 and the MOS Technology 6502 8-bit CPUs were widely used in home computers and second- and third-generation game consoles of the 1970s and 1980s. Many 8-bit CPUs or microcontrollers are the basis of today's ubiquitous embedded systems .

CONTENTS

* 1 Details * 2 Notable 8-bit CPUs * 3 See also * 4 References

DETAILS

There are 28 (256) different possible values for 8 bits. When unsigned, it has possible values ranging from 0 to 255, when signed , it has -128 to 127.

Eight-bit CPUs use an 8-bit data bus and can therefore access 8 bits of data in a single machine instruction . The address bus is typically a double octet wide (i.e. 16-bit ), due to practical and economical considerations. This implies a direct address space of only 64 KB on most 8-bit processors.

NOTABLE 8-BIT CPUS

The first commercial 8-bit processor was the Intel 8008 (1972) which was originally intended for the Datapoint 2200
Datapoint 2200
intelligent terminal . Most competitors to Intel started off with such character oriented 8-bit microprocessors. Modernized variants of these 8-bit machines are still one of the most common types of processor in embedded systems.

Another notable 8-bit CPU is the MOS Technology 6502 ; it, and variants of it, were used in a number of personal computers such as the Apple I
Apple I
and Apple II
Apple II
, the Atari 8-bit family , the BBC Micro , and the Commodore PET and Commodore VIC-20 , and in a number of video game consoles such as the Atari 2600
Atari 2600
and the Nintendo Entertainment System .

Early or popular 8-bit processors (incomplete) MANUFACTURER PROCESSOR YEAR COMMENT

Intel 8008 1972 Datapoint 2200
Datapoint 2200
compatible

Signetics 2650 1973

Intel 8080 1974 8008 source compatible

Motorola 6800 1974

Fairchild F8 1975

MOS 6502 1975 Similar to 6800, but incompatible

Microchip PIC 1975 Harvard architecture microcontroller

RCA 1802 1976

Zilog Z80 1976 8080 binary compatible

Intel 8085 1977 8080 binary compatible

Motorola 6809 1978 6800 source compatible

Zilog Z8 1978 Harvard architecture microcontroller

Intel 8051 1980 Harvard architecture microcontroller

MOS 6510 1982 Enhanced 6502 custom-made for use in the Commodore 64
Commodore 64

Ricoh 2A03 1982 6502 clone minus BCD instructions for the Nintendo Entertainment System

Zilog Z180 1985 Z80 binary compatible

Motorola 68HC11 1985

Atmel AVR 1996

Zilog EZ80 1999 Z80 binary compatible

Infineon XC800 2005

Freescale 68HC08

Hudson HuC6280

Motorola 6803

NEC 78K0

SEE ALSO

* Vasm , a free assembler

REFERENCES

* ^ Amdahl, G. M. ; Blaauw, G. A. ; Brooks, F. P. (1964). "Architecture of the IBM System/360". _IBM Journal of Research and Development_. 8 (2): 87–101. doi :10.1147/rd.82.0087 . * ^ NEC 78K0

* v * t * e

CPU technologies

ARCHITECTURE

* Turing machine * Post– Turing machine * Universal Turing machine * Quantum Turing machine * Belt machine * Stack machine * Register machine * Counter machine * Pointer machine * Random access machine * Random access stored program machine * Finite-state machine * Queue automaton * Von Neumann * Harvard (Modified ) * Dataflow * TTA * Cellular

* Artificial neural network
Artificial neural network

* Machine learning * Deep learning
Deep learning
* Neural processing unit (NPU)

* Convolutional neural network
Convolutional neural network
* Load/store architecture * Register memory architecture * Register register architecture * Endianness * FIFO * Zero-copy * NUMA * HUMA * HSA * Heterogeneous computing * Parallel computing * Amorphous computing * Reconfigurable computing * Cognitive computing * DNA computing
DNA computing
* Peptide computing * Chemical computing * Organic computing * Wetware computer * Quantum computing * Neuromorphic computing * Optical computing * Reversible computing * Unconventional computing * Hypercomputation * Ternary computer * Symmetric multiprocessing (SMP) * Asymmetric multiprocessing (AMP) * Cache hierarchy * Memory hierarchy

ISA TYPES

* ASIP * CISC * RISC * EDGE (TRIPS ) * VLIW (EPIC ) * MISC * OISC * NISC * ZISC * Comparison

ISAS

* x86 * z/Architecture * ARM * MIPS * Power Architecture
Power Architecture
( PowerPC ) * SPARC
SPARC
* VISC * Mill * Itanium
Itanium
( IA-64
IA-64
) * Alpha * Prism * SuperH * Clipper * VAX
VAX
* Unicore * PA-RISC
PA-RISC
* MicroBlaze

WORD SIZE

* 1-bit * 2-bit * 4-bit * 8-bit * 9-bit * 10-bit * 12-bit * 15-bit * 16-bit * 18-bit * 22-bit * 2 4-bit * 25-bit * 26-bit * 27-bit * 31-bit * 32-bit * 33-bit * 3 4-bit * 36-bit * 39-bit * 40-bit * 48-bit * 50-bit * 60-bit * 6 4-bit * 128-bit * 256-bit * 5 12-bit * Variable

EXECUTION

* Instruction pipelining
Instruction pipelining

* Bubble * Operand forwarding

* Out-of-order execution

* Register renaming

* Speculative execution

* Branch predictor * Memory dependence prediction

* Hazards

PARALLEL LEVEL

* Bit
Bit

* Bit-serial * Word

* Instruction

* Pipelining

* Scalar * Superscalar

* Task

* Thread * Process

* Data

* Vector

* Memory

MULTITHREADING

* Temporal * Simultaneous (SMT) ( Hyper-threading ) * Speculative (SpMT) * Preemptive * Cooperative * Clustered Multi-Thread (CMT) * Hardware scout

FLYNN\\'S TAXONOMY

* SISD
SISD
* SIMD
SIMD
( SWAR ) * SIMT * MISD
MISD

* MIMD
MIMD

* SPMD

* Addressing mode

CPU PERFORMANCE

* Instructions per second (IPS) * Instructions per clock (IPC) * Cycles per instruction (CPI) * Floating-point operations per second (FLOPS) * Transactions per second (TPS) * SUPS * Performance per watt
Performance per watt
* Orders of magnitude (computing) * Cache performance measurement and metric

CORE COUNT

* Single-core processor * Multi-core processor * Manycore processor

TYPES

* Central processing unit
Central processing unit
(CPU) * GPGPU * AI accelerator * Vision processing unit (VPU) * Vector processor * Barrel processor * Stream processor * Digital signal processor (DSP) * I/O processor/DMA controller * Network processor
Network processor
* Baseband processor * Physics processing unit (PPU) * Coprocessor * Secure cryptoprocessor
Secure cryptoprocessor
* ASIC
ASIC
* FPGA
FPGA
* FPOA * CPLD * Microcontroller * Microprocessor * Mobile processor * Notebook processor * Ultra-low-voltage processor * Multi-core processor * Manycore processor * Tile processor * Multi-chip module (MCM) * Chip stack multi-chip modules * System on a chip
System on a chip
(SoC) * Network on a chip (NoC) * Multiprocessor system-on-chip (MPSoC) * Programmable System-on-Chip ( PSoC
PSoC
)

COMPONENTS

* Execution unit (EU) * Arithmetic logic unit (ALU) * Address generation unit (AGU) * Floating-point unit (FPU) * Load-store unit (LSU) * Fixed-point unit (FXU) * Vector unit (VU) * Branch predictor * Branch execution unit (BEU) * Instruction Decoder * Instruction Scheduler * Instruction Fetch Unit * Instruction Dispatch Unit * Instruction Sequencing Unit * Unified Reservation Station * Barrel shifter
Barrel shifter
* Uncore * Sum addressed decoder (SAD) * Front-side bus
Front-side bus
* Back-side bus * Northbridge (computing) * Southbridge (computing) * Adder (electronics)
Adder (electronics)
* Binary multiplier * Binary decoder
Binary decoder
* Address decoder * Multiplexer * Demultiplexer
Demultiplexer
* Registers * Cache * Memory management unit (MMU) * Input–output memory management unit (IOMMU) * Integrated Memory Controller (IMC) * Power Management Unit (PMU) * Translation lookaside buffer (TLB) * Stack engine * Register file * Processor register * Hardware register * Memory buffer register (MBR) * Program counter
Program counter
* Microcode ROM * Datapath * Control unit * Instruction unit * Re-order buffer * Data buffer * Write buffer * Coprocessor * Electronic switch * Electronic circuit * Integrated circuit * Three-dimensional integrated circuit * Boolean circuit * Digital circuit * Analog circuit * Mixed-signal integrated circuit * Power management integrated circuit * Quantum circuit
Quantum circuit

* Logic gate

* Combinational logic * Sequential logic * Emitter-coupled logic (ECL) * Transistor–transistor logic
Transistor–transistor logic
(TTL) * Glue logic

* Quantum gate * Gate array
Gate array
* Counter (digital) * Bus (computing) * Semiconductor device
Semiconductor device
* Clock rate * CPU multiplier * Vision chip * Memristor

Power management

* APM * ACPI * Dynamic frequency scaling * Dynamic voltage scaling * Clock gating

Hardware security

* Non-executable memory (NX bit) * Bounds checking (Intel MPX) * Intel Secure Key * Hardware restriction (firmware ) * Software Guard Extensions (Intel SGX) * Trusted Execution Technology * OmniShield * Trusted Platform Module (TPM) * Secure cryptoprocessor
Secure cryptoprocessor
* Hardware security module * Hengzhi chip

RELATED

* History of general-purpose CPUs

Retrieved from "https://en.wikipedia.org/w/index.php?title= 8-bit additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy .® is a registered trademark of the Wikimedia Foundation, Inc. , a non-profit organization.

* Privacy policy * About * Disclaimers * Contact * Developers * Cookie statement * Mobile view

* *

.