Understand the difference.

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

Sm/Rm

IEC

IEC set and reset dependency (S, R)

S and R dependencies specify the internal state of an output when both set and reset conditions could be active together. An Rm input at its internal 1 state makes the affected output react as it would to S=0, R=1; an Sm input does the opposite. At 0 they have no effect.

Drawing use

Schematic

Application

Logic & signals

Reference family

IEC / Manufacturer

Form evidence

Affecting inputs labelled Sm or Rm with affected outputs labelled m. 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

An ordinary R input resets the element directly; Rm dependency states the reaction of particular outputs.

Full referenceAdd to legend

S R

IEC

IEC SR latch (rectangular form)

The simplest IEC bistable is a rectangle with inputs labelled S and R and outputs Q and complemented Q. An active S sets the element to 1 and an active R resets it to 0, with no clock involved. Negation or polarity marks show active-low inputs, as on devices built from cross-coupled NAND gates.

Drawing use

Schematic

Application

Logic & signals

Reference family

IEC / Manufacturer

Form evidence

Rectangular bistable with S and R inputs. 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 clocked SR flip-flop has 1S and 1R inputs under C1 control; the plain latch has none.

Full referenceAdd to legend

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