In computer architecture,
4-bit integers, memory addresses,
or other data units are those that are 4 bits wide. Also,
and ALU architectures are those that are based on registers, address
buses, or data buses of that size. A group of four bits is also called
a nibble and has 24 = 16 possible values.
Some of the first microprocessors had a
4-bit word length and were
developed around 1970. The TMS 1000, the world's first single-chip
microprocessor, was a
4-bit CPU; it had a Harvard architecture, with
an on-chip instruction ROM, 8-bit-wide instructions and an on-chip
data RAM with
4-bit words. The first commercial microprocessor was
the binary-coded decimal (BCD-based) Intel 4004, developed for
calculator applications in 1971; it had a
4-bit word length, but had
8-bit instructions and
HP Saturn processors, used in many
between 1984 and 2015 (including the HP 48 series of scientific
calculators) are "4-bit" (or hybrid 64-/4-bit) machines; as the Intel
4004 did, they string multiple
4-bit words together, e.g. to form a
20-bit memory address, and most of its registers have 64 bits, storing
4-bit processors were programmed in assembly language or Forth,
MARC4 Family of 4 bit Forth CPU" because of the extreme size
constraint on programs and because common programming languages (for
8-bit and larger), such as the C programming
language, do not support
4-bit data types (C requires that the size of
the char data type be at least 8 bits, and that all data types
other than bitfields have a size that is a multiple of the character
size). While larger than
4-bit values can be used by
combining more than one manually, the language has to support the
smaller values used in the combining. If not, assembly is the only
option.[dubious – discuss]
The 1970s saw the emergence of
4-bit software applications for mass
markets like pocket calculators.
In the 1970s and 1980s, a number of research and commercial computers
used bit slicing, in which the CPU's arithmetic logic unit (ALU) was
built from multiple 4-bit-wide sections, each section including a chip
such as an Am2901 or
The Zilog Z80, although it is an
8-bit microprocessor, has a 4-bit
1 Modern uses
3 List of
4 See also
6 External links
While 32- and 6
4-bit processors are more prominent in modern consumer
4-bit CPUs continue to be used (usually as part of a
microcontroller) in cost-sensitive applications that require minimal
computing power. For example, one bicycle computer specifies that it
uses a "
4-bit 1-chip microcomputer". Other typical uses include
coffee makers, infrared remote controls, and security alarms.
4-bit processors has declined relative to
8-bit or even 32-bit
processors, as they are hard to find cheaper in general computer
suppliers' stores. The simplest kinds are not available in any of
them, and others are "non-stock" and more expensive. (A few
expensive ones can be found, as of 2014[update], on eBay.)
Electronics stores still carry, as of 2014[update], non-CPU/non-MCU
4-bit chips, such as counters.
As of 2015[update], most PC motherboards, especially laptop
motherboards, use a
LPC bus (introduced in 1998) to connect the
southbridge to the motherboard firmware flash ROM (UEFI or BIOS) and
Super I/O chip.
Main article: Nibble
With 4 bits, it is possible to create 16 different values. All
single-digit hexadecimal numbers can be written with four bits.
Binary-coded decimal is a digital encoding method for numbers using
decimal notation, with each decimal digit represented by four bits.
an infrared remote control transmitter controlled by a
NEC D63GS 4-bit
NEC D63GS: a
4-bit microcontroller for infrared remote control
Olympia CD700 Desktop Calculator using the National Semiconductor MAPS
National Semiconductor MM5700CA/D bit-serial
MARC4 core – (discontinued: "Last ship date: March 7,
Samsung S3C7 (KS57 Series)
4-bit microcontrollers (RAM: 512 to 5264
nibbles, 6 MHz clock)
NEC (now Renesas) µPD612xA (discontinued), µPD613x, μPD6x
and μPD1724x infrared remote control transmitter
EM Microelectronic-Marin EM6600 family, EM6580,
National Semiconductor MAPS MM570X
Low Pin Count
^ TMS 1000 Series Data Manual (PDF). Texas Instruments. December 1976.
Retrieved July 20, 2013.
^ Mack, Pamela E. (November 30, 2005). "The Microcomputer Revolution".
^ "History in the Computing Curriculum" (PDF). Retrieved
^ "The Saturn Processor". Retrieved December 23, 2015.
^ "Guide to the Saturn Processor". Retrieved January 14, 2014.
^ "Introduction to Saturn Assembly Language". Retrieved January 14,
^ Forth Chips.
^ ISO/IEC 9899:1999 specification. p. 20, § 22.214.171.124.1.
^ ISO/IEC 9899:1999 specification. p. 37, § 126.96.36.199 (4).
^ Marshall Cline. "C++ FAQ: the rules about bytes, chars, and
4-bit integer". cplusplus.com. Retrieved November 21, 2014.
^ Masatoshi Shima; Federico Faggin; Ralph Ungermann; Michael Slater.
"Zilog Oral History Panel on the Founding of the Company and the
Development of the Z80 Microprocessor".
^ Ken Shirriff. "The Z-80 has a
^ "Cateye Commuter Manual" (PDF). Retrieved February 11, 2014.
^ a b μPD67, 67A, 68, 68A, 69
4-bit single-chip microcontroller for
infrared remote control transmission
^ Haskell, Richard. "Introduction to Digital Logic and Microprocessors
(Lecture 12.2)". Retrieved February 11, 2014.
^ Scott Mueller. "Upgrading and Repairing Laptops". 2004. p. 176.
^ David S. Lawyer. "Plug-and-Play-HOWTO: LPC Bus" 2007.
Microcontrollers - Programmer's Guide" (PDF). Atmel.
Archived from the original (PDF) on 2014-12-15. Retrieved January 14,
Bit Architecture". Atmel. Archived from the original on May
^ Product End-of-Life (EOL) Notification
4-bit single-chip microcontroller for infrared remote
^ μPD17240, 17241, 17242, 17243, 17244, 17245, 17246 4-bit
single-chip microcontrollers for small general-purpose infrared remote
Microcontrollers for Remote Controllers
^ "Mask ROM/ROMless Products 4/8bit Remote Control". Archived from the
original on October 28, 2008.
^ Robert Cravotta. "Embedded Processing Directory"
^ "EM6580 low power Flash
"Products: High Performance
S1C63 family ]".
Epson. Archived from the original on 2013-07-29.
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