Further afield
Two dozen doors to related reading
Bit-width connects to almost everything else in computer architecture. The links below lead outward into the encyclopedic and archival record — grouped so you can follow whichever thread the rest of this site pulled loose. All open external sites in a new context; we keep no trackers of where you go next.
Bit-width, level by level
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4-bit computing
en.wikipedia.org
The narrowest mainstream word: calculators, controllers, and the 4004 that started it all.
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8-bit computing
en.wikipedia.org
One byte per word — the era of home computers, game consoles and the 64 KiB ceiling.
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16-bit computing
en.wikipedia.org
Segments, megabytes, and the awkward adolescence between the home micro and the flat 32-bit PC.
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32-bit computing
en.wikipedia.org
Flat 4 GiB address spaces, virtual memory, and the platform that defined modern software.
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64-bit computing
en.wikipedia.org
The present tense: 16-exbibyte address spaces and the quiet retirement of 32-bit software.
Core concepts
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Word (computer architecture)
en.wikipedia.org
The formal notion of a machine word and its relationship to registers, addresses and instructions.
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Processor register
en.wikipedia.org
The fastest storage in the machine, and the width that most honestly defines a processor's bitness.
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Address space
en.wikipedia.org
How the address bus width becomes a memory ceiling, and how virtual memory stretches it.
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Endianness
en.wikipedia.org
Byte order for multi-byte words — big-endian versus little-endian, and why networks pick one.
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Two's complement
en.wikipedia.org
The representation that lets a fixed-width register hold signed integers and add them the same way.
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SIMD
en.wikipedia.org
Where the “128-bit” and “512-bit” of modern spec sheets actually live: vector data paths.
Landmark processors
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Intel 4004
en.wikipedia.org
The first commercially available single-chip microprocessor — 4 bits, 2,300 transistors, 1971.
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MOS Technology 6502
en.wikipedia.org
The inexpensive 8-bit chip behind the Apple II, Commodore 64, BBC Micro and the NES.
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Zilog Z80
en.wikipedia.org
The other great 8-bit workhorse — CP/M machines, the ZX Spectrum, and decades of embedded life.
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Intel 8086
en.wikipedia.org
The 16-bit chip whose segmented memory model and instruction set still echo inside every PC.
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Motorola 68000
en.wikipedia.org
The great “is it 16 or 32-bit?” exam question — and the brain of the Mac, Amiga and Genesis.
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Intel 80386
en.wikipedia.org
The processor that brought flat 32-bit addressing and protected mode to the personal computer.
Instruction-set architectures
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Instruction set architecture
en.wikipedia.org
The hardware/software contract that operand width and addressing modes are written into.
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x86
en.wikipedia.org
Four decades of backward compatibility, from the 16-bit 8086 to today's 64-bit cores.
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ARM architecture
en.wikipedia.org
The efficient RISC design that grew from a Cambridge workstation into the processor of the mobile era.
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RISC-V
en.wikipedia.org
An open, royalty-free ISA with clean 32-, 64- and 128-bit base variants reopening the conversation.
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MIPS architecture
en.wikipedia.org
A textbook RISC design that taught a generation of students and powered consoles and routers alike.
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RISC vs CISC
en.wikipedia.org
The design philosophy debate that shaped how bit-width and instruction complexity trade off.
Wider context & institutions
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Microprocessor
en.wikipedia.org
The overarching story of putting a processor on a chip, into which every era here fits.
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Moore's law
en.wikipedia.org
The transistor-density trend that made each doubling of the word affordable when it arrived.
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Transistor count
en.wikipedia.org
A running tally from the 4004's 2,300 transistors to the tens of billions on a modern die.
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Computer History Museum
computerhistory.org
Artifacts, oral histories and exhibitions documenting the machines behind every era here.
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IEEE Computer Society
computer.org
The professional body and publisher whose archives chronicle processor design as it happened.
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Central processing unit
en.wikipedia.org
The top-level article tying registers, ALU, buses and control together into one machine.
On external links. The destinations above are independent third-party sites, offered purely as further reading. We have no affiliation with them and earn nothing from your clicks; they are simply the references we would hand a curious friend. If a link has rotted by the time you reach it, the article title should be enough to find its successor.