QUASI-SYNCHRONOUS INFORMATION TRANSFER AND PHASE ALIGNMENT MEANS
FOR ENABLING SAME BACKGROUND OF THE INVENTION 5 The invention
generally refers to a method of quasisynchronously transferring
clocking-, data-, and/or control signals between two or more
data processing units and to a phase alignment means for
enabling same. FIGS. 1A-C show a block diagram and timing dia-
10 grams of how a synchronous and an asynchronous interface
work. Since they are widely known, only the important summary
points are dealt with in the following: Synchronous Interface
(FIG. 1A, B) 15 The clock signals of units A and B have the same
frequency and the same phase relationship. One data transfer can
occur every cycle via connecting cables 1 and/or 2. Any
interface delays must be adjusted to exactly align 20 the
internal clocks of both units. For a system involving a cable
and interface drivers, this may be a very difficult job to
realize. As can be seen from FIG. IB, a synchronous interface
can be used to send data from unit A to u