As in a task for development of the device it is not imposed restrictions on methods, the block diagram and elementary base of the device, it is obvious that versions of the solution of an objective can be a little. Let's consider the most acceptable from them.
There are chips of series 155, 555, 1533 and others. As any special restrictions in this development it is not shown, we will choose series 155 chips for basic elements, the most precisely suitable from the point of view of hardware expenses. As elements of formation of IVKG ROM of a series 556 which can be used together with digital chips of TTL of type.
The most acceptable option of performance of the developed device – on one payment with one or bilateral printed circuit wiring. The real size of a payment, and also socket type, is defined by a design of the general device which part is this development. However, as such information is absent, we will assume as a basis one of the standard sizes of payments and suitable for the purposes of connection of the developed device I will corrode. The highlights defining a design, the following:
For carrying out calculation it is necessary to know: types of elements, failure rate of i of elements of various types and quantity of the Ni elements of each type which are logging in. The accounting of operational conditions is consolidated to a choice of types of the elements capable to work in the set conditions. Calculation is carried out according to the following scheme:
The choice of element base is carried out by finding of a compromise between hardware expenses and speed. Considering speed of this scheme obviously use of chips of TTL for all elements except ROM.