Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

P-Q

IEC

IEC subtracter (P-Q)

The subtracter qualifier is written P minus Q. Inputs are grouped as the P and Q words with binary weights and outputs give the difference, with borrow input and output terminals for cascading. TI's overview lists it with the adder and other arithmetic qualifiers.

Drawing use: Schematic
Application: Logic & signals
Reference family: IEC / Manufacturer
Form evidence: Rectangular element with the P-Q qualifier. 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.

A distinction that matters

The Σ adder adds P and Q; an ALU may perform either under mode control.

Full reference

IEC

IEC adder (Σ)

The adder qualifier is the capital sigma. Inputs are grouped into P and Q words with binary weights, plus a carry input CI; outputs give the sum with weights and a carry output CO. TI's overview lists Σ alongside P-Q for subtraction and CPG for look-ahead carry generation.

Drawing use: Schematic
Application: Logic & signals
Reference family: IEC / Manufacturer
Form evidence: Rectangular element with Σ qualifier, P and Q inputs, CI and CO. 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. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.

A distinction that matters

A subtracter carries the P-Q qualifier instead; Σ marks an adder.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.