1-bit computing
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In computer architecture, 1-bit integers or other data units are those that are 1 bit (1/8 octet) wide. Also, 1-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers of that size.
There are no computers or microcontrollers of any kind that are exclusively 1-bit for all registers and address buses. A 1-bit register can only store two different values. This is very restrictive and therefore not enough for a program counter which, on modern systems, is implemented in an on-chip register, but is not implemented on-chip in some 1-bit systems. Opcodes for at least one 1-bit processor architecture were 4-bit and the address bus was 8-bit.
While 1-bit computing is rarely used on its own today, 1-bit serial communication is still used in modern computers, even on machines with large internal buses.
The first carbon nanotube computer from 2013 is a 1-bit one-instruction set computer (and has only 178 transistors; though it has only one instruction, it can emulate 20 MIPS instructions).[1]
1-bit
A serial computer processes data a single bit at a time. For example, the PDP-8/S was a 12-bit computer using a 1-bit ALU, processing the 12 bits serially.[2]
An example of a 1-bit computer built from discrete logic SSI chips is the Wang 500 (1970/1971) calculator[3][4] as well as the Wang 1200 (1971/1972)[5] word processor series developed by Wang Laboratories.
Other examples of 1-bit architectures are programmable logic controllers (PLCs), such as the 1969 PDP-14.[6] These were often programmed in ladder logic or in instruction list (IL). An example of such a 1-bit architecture that was marketed as a CPU is the Motorola MC14500B Industrial Control Unit (ICU),[7][8] introduced in 1977 and manufactured at least up into the mid 1990s.[8] Its manual states:
One of the computers known to be based on this CPU was the WDR 1-bit computer.[9] A typical sequence of instructions from a program for a 1-bit architecture might be:
- load digital input 1 into a 1-bit register;
- OR the value in the 1-bit register with input 2, leaving the result in the register;
- write the value in the 1-bit register to output 1.
This architecture was considered superior for programs making decisions rather than performing arithmetic computations, for ladder logic as well as for serial data processing.[7]
There are also several design studies for 1-bit architectures in academia, and corresponding 1-bit logic can also be found in programming. Several early massively parallel computers used 1-bit architectures for the processors as well. Examples include the May 1983 Goodyear MPP and the 1985 Connection Machine. By using a 1-bit architecture for the individual processors a very large array (e.g. the Connection Machine had 65,536 processors) could be constructed with the chip technology available at the time. In this case the slow computation of a 1-bit processor was traded off against the large number of processors.
See also
- Bit-serial architecture
- Bit banging
- Bit slicing
- Turing machine
- Enhanced Serial Peripheral Interface (eSPI) allows 1-bit communication
References
- ^ Page Module:Citation/CS1/styles.css has no content.Courtland, Rachel (2013-09-25). "First Computer Made From Carbon Nanotubes Debuts - The modest 1-bit, 1 kHz machine could usher in a new post-silicon era". IEEE Spectrum: Technology, Engineering, and Science News. Archived from the original on 2022-06-15. Retrieved 2021-04-18.
- ^ Page Module:Citation/CS1/styles.css has no content."III. System Logic - 3.4. Control Circuits - 3.4.1 Adder". PDP-8/S Maintenance Manual (PDF) (4th printing ed.). Maynard, Massachusetts, US: Digital Equipment Corporation. August 1969 [October 1967]. pp. 3-14 – 3-15. F-87S. Archived (PDF) from the original on 2021-10-23. Retrieved 2022-06-15. (191 pages)
- ^ Page Module:Citation/CS1/styles.css has no content.Wasserman, Katie (March 2006) [January 2004]. "LED calculators rule her house". Computer Collector Newsletter / Technology Rewind (Interview). Interviewed by Koblentz, Evan. Retrieved 2017-05-20.
Probably my most favorite is the Wang 500. It's got several unique things about it: a very unusual ROM memory made of hundreds of long enamel-coated wires wrapped around iron cores; a super-fast single-bit CPU built out of SSI logic chips; and of course tons of really cool-looking colorful keys.
{{cite interview}}: CS1 maint: deprecated archival service (link) - ^ Page Module:Citation/CS1/styles.css has no content.Product Service - Schematic manual (PDF). Wang Laboratories, Inc. 1974. 03-0019-0. Archived (PDF) from the original on 2017-05-20. Retrieved 2017-05-20.
- ^ Page Module:Citation/CS1/styles.css has no content.Battle, Jim (2010-03-07). "Wang 1200 - Wang WP History". Archived from the original on 2017-05-21. Retrieved 2017-05-21.
- ^ Page Module:Citation/CS1/styles.css has no content."DEC PDP-14 Industrial Controller".
- ^ a b Page Module:Citation/CS1/styles.css has no content.Gregory, Vern; Dellande, Brian; DiSilvestro, Ray; Malarkey, Terry; Smith, Phil; Hadley, Mike (1977). Motorola MC14500B Industrial Control Unit Handbook - Theory and Operation of a CMOS one-bit processor compatible with B series CMOS devices (PDF). Motorola Semiconductor Products Inc. 33-B78/8.0. Archived (PDF) from the original on 2022-04-01. Retrieved 2017-05-20. (NB. Also available in German language under the title "Motorola MC14500B Industrial Control Unit Handbuch - Theorie und Anwendung eines Ein-Bit-CMOS-Prozessors".)
- ^ a b Page Module:Citation/CS1/styles.css has no content."Industrial Control Unit MC14500B". Motorola CMOS Logic Data (PDF). Semiconductor Technical Data (revision 3 ed.). Motorola. 1995. pp. 306–313. Archived (PDF) from the original on 2017-05-20. Retrieved 2012-08-01.
- ^ Page Module:Citation/CS1/styles.css has no content.Ludwig, Volker; Paschenda, Klaus; Schepers, Heinz; Terglane, Hermann-Josef; Grannemann, Klaus; John, Burkhard; Komar, Hermann; Meinersen, Ludwig (1986). Fast alles über den WDR-1-Bit-Computer (PDF) (in Deutsch). Neuss & Recklinghausen, Germany: DATANorf. Archived (PDF) from the original on 2017-05-20. Retrieved 2017-05-20.
Further reading
- Page Module:Citation/CS1/styles.css has no content.Mueller, Dieter (2005) [2004]. "The famous/infamous MC14500". Archived from the original on 2017-08-03. Retrieved 2018-07-18.
- Page Module:Citation/CS1/styles.css has no content.Mueller, Dieter (2008). "MC14500 and arithmetic". Archived from the original on 2017-05-20. Retrieved 2018-07-18.
- Page Module:Citation/CS1/styles.css has no content.Mueller, Dieter (2008). "A MC14500 modification". Archived from the original on 2017-03-20. Retrieved 2018-07-18.
External links
- Page Module:Citation/CS1/styles.css has no content.Schembri, Thierry; Bizoirre, Sylvain; Boisseau, Olivier; Chauvaud, Pierre-Emmanuel. "WDR-1-Bit Computer". OLD-COMPUTERS.COM. Archived from the original on 2017-05-20. Retrieved 2017-05-20.
