Quick-Return Linkage

Specifications

Informal

A Quick-Return Linkage (QRL for short) has two input terminals (a and d) and two output terminals (b and c). Input a and output b alternate (together forming a passive handshake channel), as do output c and input d (together forming an active handshake channel). Every 4 phases abab match 4 phases cdcd, the first two phases of ab enclose the first two phases of cd, the remaining phases may occur in parallel, constituting the `quick return' (to zero voltage level).

XDI

Schematic diagram for a Quick-Return Linkage:

[Zoom|FIG]

XDI state graph for a Quick-Return Linkage:

[Zoom|FIG]

Specification in XDI model.

Verdect

Specification in Verdect:


define QRL( a?, b!, c!, d? ) =
       pref ( a? ; *[ c! ; d? ; b! ; a?
                    ; ((b! ; a?) || (c! ; d?))
                    ]
            )
end

Also available through this link