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16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The
range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...
of integer values that can be stored in 16 bits depends on the integer representation used. With the two most common representations, the range is 0 through 65,535 (216 − 1) for representation as an ( unsigned)
binary number A binary number is a number expressed in the base-2 numeral system or binary numeral system, a method of mathematical expression which uses only two symbols: typically "0" (zero) and "1" ( one). The base-2 numeral system is a positional notation ...
, and −32,768 (−1 × 215) through 32,767 (215 − 1) for representation as two's complement. Since 216 is 65,536, a processor with 16-bit memory addresses can directly access 64 KB (65,536 bytes) of
byte-addressable Byte addressing in hardware architectures supports accessing individual bytes. Computers with byte addressing are sometimes called ''byte machines,'' in contrast to ''word-addressable'' architectures, ''word machines'', that access data by word. ...
memory. If a system uses segmentation with 16-bit segment offsets, more can be accessed.


16-bit architecture

The MIT Whirlwind ( 1951) was quite possibly the first-ever 16-bit computer. It was an unusual word size for the era; most systems used
six-bit character code A six-bit character code is a character encoding designed for use on computers with word lengths a multiple of 6. Six bits can only encode 64 distinct characters, so these codes generally include only the upper-case letters, the numerals, some pun ...
and used a word length of some multiple of 6-bits. This changed with the effort to introduce
ASCII ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...
, which used a 7-bit code and naturally led to the use of an 8-bit multiple which could store a single ASCII character or two
binary coded decimal In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for ...
digits. The 16-bit word length thus became more common in the 1960s, especially on minicomputer systems. Early 16-bit computers ( 1965–70) include the
IBM 1130 The IBM 1130 Computing System, introduced in 1965, was IBM's least expensive computer at that time. A binary 16-bit machine, it was marketed to price-sensitive, computing-intensive technical markets, like education and engineering, succeeding th ...
, the HP 2100, the Data General Nova, and the DEC PDP-11. Early
16-bit microprocessors 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two most ...
, often modeled on one of the mini platforms, began to appear in the 1970s. Examples ( 1973–76) include the five-chip National Semiconductor IMP-16 (1973), the two-chip NEC μCOM-16 (1974), the three-chip Western Digital MCP-1600 (1975), and the five-chip Toshiba T-3412 (1976). Early single-chip 16-bit microprocessors ( 1975–76) include the
Panafacom Panafacom was a Japanese microprocessor design firm formed on 2 July 1973 by a consortium including Fujitsu, Fuji Electric and Matsushita (Panasonic). The company was formed to design and manufacture the MN1610, a 16-bit microprocessor. It was re ...
MN1610 (1975),
National Semiconductor PACE National Semiconductor's IPC-16A PACE, short for "Processing and Control Element", was the first commercial single-chip 16-bit microprocessor, announced in late 1974. It was a single-chip implementation of their early 1973 five-chip IMP-16 archite ...
(1975),
General Instrument CP1600 The CP1600 is a 16-bit microprocessor created in a partnership between General Instrument and Honeywell, introduced in February 1975. It is one of the first single-chip 16-bit processors. The overall design bore a strong resemblance to the PDP-11. ...
(1975), Texas Instruments TMS9900 (1976),
Ferranti F100-L The Ferranti F100-L was a 16-bit microprocessor family announced by Ferranti in 1976 which entered production in 1977. It was the first microprocessor designed in Europe, and among the first 16-bit single-chip CPUs. It was designed with military us ...
, and the HP BPC. Other notable 16-bit processors include the Intel 8086, the Intel 80286, the
WDC 65C816 The W65C816S (also 65C816 or 65816) is an 8/16-bit microprocessor (MPU) developed and sold by the Western Design Center (WDC). Introduced in 1985, the W65C816S is an enhanced version of the WDC 65C02 8-bit MPU, itself a CMOS enhancement of the ve ...
, and the Zilog Z8000. The
Intel 8088 The Intel 8088 ("''eighty-eighty-eight''", also called iAPX 88) microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 has an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and ...
was
binary compatible Binary-code compatibility (binary compatible or object-code-compatible) is a property of a computer system, meaning that it can run the same executable code, typically machine code for a general-purpose computer CPU, that another computer syst ...
with the Intel 8086, and was 16-bit in that its registers were 16 bits wide, and arithmetic instructions could operate on 16-bit quantities, even though its external bus was 8 bits wide. A 16-bit integer can store 216 (or 65,536) distinct values. In an unsigned representation, these values are the integers between 0 and 65,535; using two's complement, possible values range from −32,768 to 32,767. Hence, a processor with 16-bit memory addresses can directly access 64 KB of
byte-addressable Byte addressing in hardware architectures supports accessing individual bytes. Computers with byte addressing are sometimes called ''byte machines,'' in contrast to ''word-addressable'' architectures, ''word machines'', that access data by word. ...
memory. 16-bit processors have been almost entirely supplanted in the personal computer industry, and are used less than 32-bit (or 8-bit) CPUs in embedded applications.


16/32-bit Motorola 68000 and Intel 386SX

The
Motorola 68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector ...
is sometimes called 16-bit because of the way it handles basic arithmetic. The instruction set was based on
32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculati ...
numbers and the internal registers were 32 bits wide, so by common definitions, the 68000 is a 32-bit design. Internally, 32-bit arithmetic is performed using two 16-bit operations, and this leads to some descriptions of the system as 16-bit, or "16/32". Such solutions have a long history in the computer field, with various designs performing math even 1-bit at a time, known as "serial arithmetic", while most designs by the 1970s processed at least a few bits at a time. A common example is the Data General Nova, which was a 16-bit design that performed 16-bit math as a series of four 4-bit operations. 4-bits was the word size of a widely available single-chip ALU and thus allowed for inexpensive implementation. Using the definition being applied to the 68000, the Nova would be a 4-bit computer, or 4/16. Not long after the introduction of the Nova a second version was introduced, the SuperNova, which included four of the 4-bit ALUs running in parallel to perform math 16 bits at a time and therefore offer higher performance. This was invisible to the user and the programs, which always used 16-bit instructions and data. In a similar fashion, later 68000-family members, like the Motorola 68020, had 32-bit ALUs. One may also see references to systems being, or not being, 16-bit based on some other measure. One common one is when the address space is not the same size of bits as the internal registers. Most 8-bit CPUs of the 1970s fall into this category; the MOS 6502,
Intel 8080 The Intel 8080 (''"eighty-eighty"'') is the second 8-bit microprocessor designed and manufactured by Intel. It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibil ...
,
Zilog Z80 The 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 ...
and most others had 16-bit address space which provided 64 KB of address space. This also meant address manipulation required two instruction cycles. For this reason, most processors had special 8-bit addressing modes, the
zero page The zero page or base page is the block of memory at the very beginning of a computer's address space; that is, the page whose starting address is zero. The size of a page depends on the context, and the significance of zero page memory versus ...
, improving speed. This sort of difference between internal register size and external address size remained in the 1980s, although often reversed, as memory costs of the era made a machine with 32-bit addressing, 2 or 4 GB, a practical impossibility. For example, the 68000 exposed only 24 bits of addressing on the DIP, limiting it to a still huge (for the era) 16 MB. A similar analysis applies to Intel's
80286 The Intel 80286 (also marketed as the iAPX 286 and often called Intel 286) is a 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non- multiplexed address and data buses and also the ...
CPU replacement, called the
386SX The Intel 386, originally released as 80386 and later renamed i386, is a 32-bit microprocessor introduced in 1985. The first versions had 275,000 transistorsALU and internal 32-bit data paths with a 16-bit external bus and 24-bit addressing of the processor it replaced.


16-bit application

In the context of IBM PC compatible and
Wintel Wintel (portmanteau of Windows and Intel) is the partnership of Microsoft Windows and Intel producing personal computers using Intel x86-compatible processors running Microsoft Windows. Background By the early 1980s, the chaos and incompatibil ...
platforms, a 16-bit application is any software written for
MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few oper ...
, OS/2 1.x or early versions of Microsoft Windows which originally ran on the 16-bit
Intel 8088 The Intel 8088 ("''eighty-eighty-eight''", also called iAPX 88) microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 has an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and ...
and Intel 80286 microprocessors. Such applications used a 20-
bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented ...
or 24-bit segment or selector-offset address representation to extend the range of addressable memory locations beyond what was possible using only 16-bit addresses. Programs containing more than 216
byte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable uni ...
s (65,536
byte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable uni ...
s) of instructions and data therefore required special instructions to switch between their 64-kilobyte segments, increasing the complexity of programming 16-bit applications.


List of 16-bit CPUs

* Angstrem **
1801 series CPU Eighteen or 18 may refer to: * 18 (number), the natural number following 17 and preceding 19 * one of the years 18 BC, AD 18, 1918, 2018 Film, television and entertainment * ''18'' (film), a 1993 Taiwanese experimental film based on the shor ...
*
Data General Data General Corporation was one of the first minicomputer firms of the late 1960s. Three of the four founders were former employees of Digital Equipment Corporation (DEC). Their first product, 1969's Data General Nova, was a 16-bit minicomputer ...
** Nova ** Eclipse * Digital Equipment Corporation **
PDP-11 The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold ...
(for LSI-11, see Western Digital, below) *** DEC J-11 *** DEC T-11 * EnSilica ** eSi-1600 * Fairchild Semiconductor ** 9440 MICROFLAME * Ferranti **
Ferranti F100-L The Ferranti F100-L was a 16-bit microprocessor family announced by Ferranti in 1976 which entered production in 1977. It was the first microprocessor designed in Europe, and among the first 16-bit single-chip CPUs. It was designed with military us ...
** Ferranti F200-L * General Instrument ** CP1600 * Hewlett-Packard ** HP 21xx/2000/1000/98xx/BPC ** HP 3000 *
Honeywell Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building technologies, performance ma ...
** Honeywell Level 6/DPS 6 * IBM **
1130 Year 1130 ( MCXXX) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. Events * January 22 – Jin–Song Wars: Jin forces take Hangzhou. * February 4 – Jin–Song Wars: Jin forces ...
/
1800 As of March 1 ( O.S. February 18), when the Julian calendar acknowledged a leap day and the Gregorian calendar did not, the Julian calendar fell one day further behind, bringing the difference to 12 days until February 28 ( O.S. February 16) ...
** System/7 **
Series/1 The IBM Series/1 is a 16-bit minicomputer, introduced in 1976, that in many respects competed with other minicomputers of the time, such as the PDP-11 from Digital Equipment Corporation and similar offerings from Data General and HP. The Seri ...
**
System/36 The IBM System/36 (often abbreviated as S/36) was a midrange computer marketed by IBM from 1983 to 2000 - a multi-user, multi-tasking successor to the System/34. Like the System/34 and the older System/32, the System/36 was primarily pro ...
*
Infineon Infineon Technologies AG is a German semiconductor manufacturer founded in 1999, when the semiconductor operations of the former parent company Siemens AG were spun off. Infineon has about 50,280 employees and is one of the ten largest semicon ...
**
XE166 family The Infineon XE166 family is a 16-bit microcontroller family, first introduced in 2007. The XE166 can be found in applications like servo drivers, appliance motors, industrial pumps, transportation and power supplies. Key features The XE166 family ...
** C166/C167 family ** XC2000 * Intel ** Intel 8086/
Intel 8088 The Intel 8088 ("''eighty-eighty-eight''", also called iAPX 88) microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 has an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and ...
**
Intel 80186 The Intel 80186, also known as the iAPX 186, or just 186, is a microprocessor and microcontroller introduced in 1982. It was based on the Intel 8086 and, like it, had a 16-bit external data bus multiplexed with a 20-bit address bus. The 80188 ...
/ Intel 80188 ** Intel 80286 **
Intel MCS-96 The Intel MCS-96 is a family of microcontrollers (MCU) commonly used in embedded systems. The family is often referred to as the 8xC196 family, or 80196, the most popular MCU in the family. These MCUs are commonly used in hard disk drives, modems, ...
* Lockheed ** MAC-16 *
MIL-STD-1750A MIL-STD-1750A or 1750A is the formal definition of a 16-bit computer instruction set architecture (ISA), including both required and optional components, as described by the military standard document MIL-STD-1750A (1980). Since August 1996, it ha ...
* Motorola ** Motorola 68HC12 ** Motorola 68HC16 * National Semiconductor ** IMP-16 ** PACE/INS8900 * NEC ** μCOM-16 **
NEC V20 The NEC V20 is a microprocessor that was designed and produced by NEC. It is both pin compatible and object code compatible with the Intel 8088, with an instruction set architecture (ISA) similar to that of the Intel 80188 with some extension ...
and V30 *
Panafacom Panafacom was a Japanese microprocessor design firm formed on 2 July 1973 by a consortium including Fujitsu, Fuji Electric and Matsushita (Panasonic). The company was formed to design and manufacture the MN1610, a 16-bit microprocessor. It was re ...
** MN1610 * Renesas ** Renesas M16C (16-bit registers, 24-bit address space) *
Ricoh is a Japanese multinational imaging and electronics company. It was founded by the now-defunct commercial division of the Institute of Physical and Chemical Research (Riken) known as the ''Riken Concern'', on 6 February 1936 as . Ricoh's hea ...
**
Ricoh 5A22 The Ricoh 5A22 is an 8/16-bit microprocessor produced by Ricoh for the Super Nintendo Entertainment System (SNES) video game console. It is based on the 8/16-bit WDC 65C816, which was developed between 1982 and 1984 for the Apple IIGS personal ...
(WDC 65816 clone used in SNES) * Texas Instruments ** Texas Instruments TMS9900 **
TI MSP430 The MSP430 is a mixed-signal microcontroller family from Texas Instruments, first introduced on 14 February 1992. Built around a CPU, the MSP430 is designed for low cost and, specifically, low power consumption embedded applications. Applica ...
* Toshiba ** T-3412 * Western Design Center ** WDC 65816/65802 * Western Digital **
MCP-1600 The MCP-1600 is a multi-chip 16-bit microprocessor introduced by Western Digital in 1975 and produced through the early 1980s. Used in the Pascal MicroEngine, the WD16 processor in the Alpha Microsystems AM-100, and the DEC LSI-11 microcomput ...
*** used in the DEC LSI-11 *** used in the
Pascal MicroEngine Pascal MicroEngine is a series of microcomputer products manufactured by Western Digital from 1979 through the mid-1980s, designed specifically to run the UCSD p-System efficiently. Compared to other microcomputers, which use a machine language p-c ...
*** used in the WD16 * Xerox **
Alto The musical term alto, meaning "high" in Italian (Latin: '' altus''), historically refers to the contrapuntal part higher than the tenor and its associated vocal range. In 4-part voice leading alto is the second-highest part, sung in choruse ...
* Zilog ** Zilog Z8000


See also

* * *
74181 The 74181 is a 4-bit slice arithmetic logic unit (ALU), implemented as a 7400 series TTL integrated circuit. The first complete ALU on a single chip, it was used as the arithmetic/logic core in the CPUs of many historically significant minicomp ...
(key component of some early 16-bit and other CPUs) *
Audio bit depth In digital audio using pulse-code modulation (PCM), bit depth is the number of bits of information in each sample, and it directly corresponds to the resolution of each sample. Examples of bit depth include Compact Disc Digital Audio, whic ...
– as 16-bit is the most common bit depth used, e.g. on
CD audio Compact Disc Digital Audio (CDDA or CD-DA), also known as Digital Audio Compact Disc or simply as Audio CD, is the standard format for audio compact discs. The standard is defined in the ''Red Book'', one of a series of Rainbow Books (named f ...
.


References

{{Authority control
16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mos ...