Logical Design of Digital Systems

Experiment $1$: data$-$traffic in digital circuits

$1\mathrm{.}6$ Data Transfer via a Bus

It is often necessary to transfer $8-$ or $16-$bit words in $4-$bit sections via the same conduction for processing and administering data in digital technique. This principle is e$.$g$.$ used concerning input and output units for systems of processors.

The following circuit is supposed to be simulated. The components that are used are a RAM $(74170,$ a $4$x$4$ bit registers with open$-$collector$)$ and two $4-$bit D$-$type$-$registers with a tristate output $74$LS$173$A$.$

Figure $1\mathrm{.}11$: Data transfer via a bus

Q$22$: Why are the pins $9,10(DE$ in the circuit$)$ as well as in the circuit$)$ connected with each other? Which functions do the inputs have?

Q$23$: What is the task of pin $15$ at the register?

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