Intro (Claim and Warrant)
In this activity we basicallly just created a stronger/more powerful version of the SSI Asynchronous Counters. Using a 74LS93 Logic Converter we created a Medium Scale Integration Asynchronous Counter. The main differences between the SSI and the MSI Counters is that the SSI Counters used binary (provided by AOI through a clock) and converted it to a display, while the MSI Counters use a 74LS93 which converts clock impulses straight into binary which is then converted by the Hex Display to display numbers. While the 74LS93 makes counting upwards easier and faster, it is limited in its abilities as one cannot count backward or choose what number they which to start counting at (i.e. counting from 6-2 or 2-6 would be impossible).
DATA
Below is a video of the basic circuit working that counts from 0-9
After creating that we created a modified version that counts from 0-C (because it counts in HEX)
Modification
After creating the basic circuit we created a modified version with switches that either paused or restarted the counting sequence. Unfortunately the recording sofware I used did not allow you to click on the screen while recording. So without video, the picture on the left shows S1 being deactivated which cut power to the clock, stopping the circuit from counting (pausing it on the same number), when S1 was reactivated, power was again supplied and the circuit continued to count. In the picture on the right, S2 is deactivated and because it is connected to RO2 (which is basically like the Preset or Clear for this the 74LS93) the circuit stops counting and resets back to 0, when S2 is reactivated the circuit continues counting, however this time starting at 0.
Side Note
In order to make the circuit more cost affective, one should use only NOR logic rather than a combonation of NOR and AOI.