1-bit architecture

From HandWiki
Jump to: navigation, search

A 1-bit computer architecture is an instruction set architecture for a processor that has datapath widths and data register widths of 1 bit (1/8 octet) wide.

An example of a 1-bit computer built from discrete logic SSI chips[1][2] were the Wang 700 (1968/1970)[3] and Wang 500 (1970/1971)[4] calculator as well as the Wang 1200 (1971/1972)[5] word processor series of Wang Laboratories.

An example of a 1-bit architecture that was actually marketed as a CPU is the Motorola MC14500B Industrial Control Unit (ICU),[6][7] introduced in 1977 and manufactured at least up into the mid 1990s.[7] One of the computers known to be based on this CPU was the WDR 1-bit computer.[8] 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.[6]

There are also several design studies for 1-bit architectures in academia, and corresponding 1-bit logic can also be found in programming.

Other examples of 1-bit architectures are programmable logic controllers (PLCs), programmed in instruction list (IL).

Several early massively parallel computers used 1-bit architectures for the processors as well. Examples include the Goodyear MPP and the 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.

1-bit CPUs can meanwhile be considered obsolete, not many kinds have been produced and none are known to be available in the major computer component stores (as of 2016, a few on eBay[9]). The Finnish company Partco still sells MC14500B as spare part in 2017.[10]

See also


  1. 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.
  2. Product Service - Schematic manual. Wang Laboratories, Inc.. 1974. 03-0019-0. http://www.thebattles.net/oddments/wang/Wang_500_schematics.pdf. Retrieved 2017-05-20. 
  3. "Programmierbare Rechner der 3. Generation mit einfacher IC-Technik" (in German). Kelkheim/Taunus, Germany: technikum29. Wang 700 & Wang 500. http://www.technikum29.de/de/rechnertechnik/ic-technik. 
  4. "Wang Model 500 programmable calculator". Computer History Museum (CHM). http://www.computerhistory.org/collections/catalog/X222.83. 
  5. "Wang 1200 - Wang WP History". 2010-03-07. http://www.wang1200.org/history.html. 
  6. 6.0 6.1 Motorola MC14500B Industrial Control Unit Handbook - Theory and Operation of a CMOS one-bit processor compatible with B series CMOS devices. Motorola Semiconductor Products Inc.. 1977. 33-B78/8.0. http://tinymicros.com/mediawiki/images/e/ec/MC14500B_Handbook.pdf. 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".)
  7. 7.0 7.1 Industrial Control Unit MC14500B. Semiconductor Technical Data (revision 3 ed.). Motorola. 1995. pp. 306–313. http://www.brouhaha.com/~eric/retrocomputing/motorola/mc14500b/mc14500brev3.pdf. Retrieved 2012-08-01. 
  8. (in German) Fast alles über den WDR-1-Bit-Computer. Neuss, Germany: DATANorf. 1986. http://wdr-1-bit-computer.talentraspel.de/documents/wdr_1-40.pdf. Retrieved 2017-05-20. 
  9. http://www.ebay.com/itm/Motorola-IC-MC14500B-MC14500BCL-100-NEW-/320837692605
  10. "CMOS-LOGIC IC 4500 DIP16". http://www.partco.biz/verkkokauppa/product_info.php?products_id=2532&language=en. "Also known as MC14500BCP" 

Further reading

External links

Hostmonster hHosting Tier.Net hosting HandWiki ads