{"schemaVersion":1,"slug":"iec-arithmetic-logic-unit","name":"IEC arithmetic logic unit (ALU)","kind":"symbol","abbreviation":"ALU","aliases":["ALU element","IEC ALU symbol","arithmetic logic unit block"],"category":"logic-signals","drawingTypes":["Schematic"],"referenceFamilies":["IEC","Manufacturer"],"summary":"IEC element marked ALU, performing arithmetic or logic functions on two words as chosen by mode inputs.","description":["The ALU qualifier identifies an element that can perform several arithmetic and logic operations on input words P and Q. Function-select inputs use M dependency or a binary grouping to choose the operation, and outputs include the result, carry and often a P=Q flag. Because the function table is large, the symbol usually refers to a table on the drawing or in the datasheet.","ALU symbols appear in processor and controller block diagrams and in legacy logic boards. On a modern control drawing they mainly document programmable logic or explain how a processor module handles signals.","The ALU qualifier does not list the operations. A function table is essential and should be referenced explicitly. Preserve the mode-select signal names and the carry interpretation when comparing the symbol with that table."],"readingNotes":["Find the function table referenced by the mode inputs.","Check carry and comparison outputs."],"drawingChecklist":["Mark the element ALU.","Reference the function table.","Show carry and flag outputs."],"distinction":"The Σ element only adds; the ALU selects among many operations, including subtraction and logic functions.","facts":[{"label":"Qualifier","value":"ALU"},{"label":"Function selection","value":"Mode inputs referencing a table"},{"label":"Artwork scope","value":"Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic"}],"references":[{"sourceId":"s28-ti-ieee91-logic-symbols","relevance":"Lists ALU as a general qualifier."}],"related":["iec-full-adder","iec-magnitude-comparator","binary-full-adder"],"artwork":"s28-iec-arithmetic-logic-unit","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Rectangular element with ALU qualifier and mode-select inputs","reference":"Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier."},"plainEnglish":{"title":"What does IEC arithmetic logic unit (ALU) mean?","introduction":"The ALU additional drawing mark identifies an element that can perform several arithmetic and logic operations on input words P and Q. Function-select inputs use M dependency or a binary grouping to choose the operation, and outputs include the result, carry and often a P=Q flag. Because the function table is large, the symbol usually refers to a table on the drawing or in the datasheet.","example":"ALU symbols appear in processor and controller block diagrams and in legacy logic boards. On a modern control drawing they mainly document programmable logic or explain how a processor module handles signals.","drawings":"The ALU additional drawing mark does not list the operations. A function table is essential and should be referenced explicitly. Preserve the mode-select signal names and the carry interpretation when comparing the symbol with that table.","terms":[{"name":"Signal","meaning":"Electrical information passed between devices, rather than necessarily the main power supply."},{"name":"Schematic","meaning":"A drawing showing function and connections rather than physical appearance."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)","url":"https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf"}],"detail":"IEC element marked ALU, performing arithmetic or logic functions on two words as chosen by mode inputs. The Σ element only adds; the ALU selects among many operations, including subtraction and logic functions.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-arithmetic-logic-unit","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-arithmetic-logic-unit.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"s28-ti-ieee91-logic-symbols","title":"Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)","publisher":"Texas Instruments","url":"https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf","type":"manufacturer","scope":"Public explanation of rectangular logic symbols, general qualifiers, input and output qualifiers, dependency notation, bistable elements and coders, consistent with IEC 617-12 work.","checkedOn":"2026-10-28","reuse":"link-only","relevance":"Lists ALU as a general qualifier."}]}