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

1S 1R

IEC

IEC clocked SR flip-flop

Adding the C1 prefix to S and R makes them synchronous: they act only when C1 is active or on its active transition. The element therefore combines set-reset storage with clocking, which keeps state changes aligned with the rest of a synchronous system.

Drawing use: Schematic
Application: Logic & signals
Reference family: IEC / Manufacturer
Form evidence: Rectangular bistable with 1S, 1R and C1 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.

A distinction that matters

The unclocked IEC SR latch acts immediately on S and R.

Full reference

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 reference

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