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In computer architecture, 4-bit integers, memory addresses, or other data units are those that are at most 4 bits wide. Also, 4-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size.
The first microprocessors had a 4-bit word length and were developed around 1970. 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 12-bit addresses.
Details [edit]
The Intel 4004, the world's first commercially available single-chip microprocessor, was a BCD-based 4-bit CPU. The F-14 Tomcat's Central Air Data Computer (or F14 CADC) was created a year before the 4004, but its existence was classified by the United States Navy until 1997. Also, the Saturn processors, used in calculators such as the commonly used HP-48 scientific calculator, are basically 4-bit machines, although they string multiple 4-bit words together, e.g. to form a 20-bit memory address.
The 1970s saw the emergence of 4-bit software applications for mass markets like pocket calculators.
With 4 bits, it is possible to create 16 different values. All single digit hexadecimal numbers can be written with 4 bits. Binary-coded decimal is a digital encoding method for numbers using decimal notation, with each decimal digit represented by four bits.
| Binary |
Octal |
Decimal |
Hexadecimal |
| 0000 |
0 |
0 |
0 |
| 0001 |
1 |
1 |
1 |
| 0010 |
2 |
2 |
2 |
| 0011 |
3 |
3 |
3 |
| 0100 |
4 |
4 |
4 |
| 0101 |
5 |
5 |
5 |
| 0110 |
6 |
6 |
6 |
| 0111 |
7 |
7 |
7 |
| 1000 |
10 |
8 |
8 |
| 1001 |
11 |
9 |
9 |
| 1010 |
12 |
10 |
A |
| 1011 |
13 |
11 |
B |
| 1100 |
14 |
12 |
C |
| 1101 |
15 |
13 |
D |
| 1110 |
16 |
14 |
E |
| 1111 |
17 |
15 |
F |
List of 4-bit Processors [edit]
See also [edit]
References [edit]
- ^ (atmel.com)
- ^ μPD67, 67A, 68, 68A, 69 4-bit single-chip microcontroller for infrared remote control transmission
- ^ μPD6P9 4-bit single-chip microcontroller for infrared remote control transmission
- ^ μPD17240, 17241, 17242, 17243, 17244, 17245, 17246 4-bit single-chip microcontrollers for small general-purpose infrared remote control transmitters
- ^ Microcontrollers for Remote Controllers
- ^ http://www.necel.com/micro/en/product/mr_48_remocon.html[dead link]
External links [edit]
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