IEEE standard that defines logic values used in electronic design
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Character literals[1]
Character
Value
'U'
uninitialized
'X'
strong drive, unknown logic value
'0'
strong drive, logic zero
'1'
strong drive, logic one
'Z'
high impedance
'W'
weak drive, unknown logic value
'L'
weak drive, logic zero
'H'
weak drive, logic one
'-'
don't care
The IEEE 1164 standard (Multivalue Logic System for VHDL Model Interoperability) is a technical standard published by the IEEE in 1993. It describes the definitions of logic values to be used in electronic design automation, for the VHDL hardware description language.[2] It was sponsored by the Design Automation Standards Committee of the Institute of Electrical and Electronics Engineers (IEEE). The standardization effort was based on the donation of the Synopsys MVL-9 type declaration.
The primary data type std_ulogic (standard unresolved logic) consists of nine character literals (see table on the right).[1] This system promoted a useful set of logic values that typical CMOS logic designs could implement in the vast majority of modeling situations, including:
'Z' literal to make tri-state buffer logic easy
'H' and 'L' weak drives to permit wired-AND and wired-OR logic.
'U' for default value for all object declarations so that during simulations uninitialized values are easily detectable and thus easily corrected if necessary.
In VHDL, the hardware designer makes the declarations visible via the following library and use statements:
libraryIEEE;useIEEE.std_logic_1164.all;
^ ab"VHDL and Logic Synthesis". Retrieved 22 January 2010.
^"IEEE 1164-1993 – IEEE Standard Multivalue Logic System for VHDL Model Interoperability (Std_logic_1164)". standards.ieee.org. Retrieved 25 September 2018.
The IEEE1164 standard (Multivalue Logic System for VHDL Model Interoperability) is a technical standard published by the IEEE in 1993. It describes the...
rules. In addition to IEEE standard 1164, several child standards were introduced to extend functionality of the language. IEEE standard 1076.2 added...
competing VHDL, a dedicated standard for multi-valued logic exists as IEEE1164 with nine levels. System tasks are available to handle simple I/O and...
chosen for implementation convenience (see Karnaugh map § Don't cares). IEEE1164 defines 9 logic states for use in electronic design automation. The standard...
(WiMAX) is a family of wireless broadband communication standards based on the IEEE 802.16 set of standards, which provide physical layer (PHY) and media access...
the top of a design unit: library ieee; use ieee.std_logic_1164.all; -- standard unresolved logic UX01ZWLH- use ieee.numeric_std.all; -- for the signed...
Quantum Lovász Number". IEEE Transactions on Information Theory. 59 (2). Institute of Electrical and Electronics Engineers (IEEE): 1164–1174. arXiv:1002.2514...
behavioral and structural". Example of dataflow of VHDL: LIBRARY IEEE; USE IEEE.STD_LOGIC_1164.ALL; ENTITY not1 IS PORT( a : IN STD_LOGIC; b : OUT STD_LOGIC;...
of Electrical and Electronics Engineers (IEEE) Computer Society and Standards Association. It oversees IEEE Standards that are related to computer-aided...
endmodule The generated VHDL code looks as follows: library IEEE; use IEEE.std_logic_1164.all; use IEEE.numeric_std.all; use std.textio.all; use work.pck_myhdl_06...
amplitude modulators," IEEE Transactions on Circuits and Systems, Vol. CAS-34, No. 10, Oct. 1987, pp. 1161–1164. "Fellow Class of 2005". IEEE. Retrieved 30 October...
ropes were made). The Grote Kerk was probably established between 1156 and 1164 and has been expanded, damaged and rebuilt. To the north of the old harbour...
rhinovirus-2". The American Review of Respiratory Disease. 141 (2): 352–56. doi:10.1164/ajrccm/141.2.352. PMID 2154152. b. Patricia Queen Samour; Kathy King Helm...
to 2015 in the Mu Us Sandy Land, Northern China". Sustainability. 9 (7): 1164. doi:10.3390/su9071164. ISSN 2071-1050. Chen, Yu Fu; Yu, Fei Hai; Dong, Ming...
Principles of Stratigraphy. Blackwell Publishing. p. 116. ISBN 978-1-4051-1164-5. Fuller, J. G. C. M. (2007-07-17). "Smith's other debt, John Strachey,...
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