Student "edition" found at {csi dot journalspace dot com}.

Maybe I shouldn't have started this blog now, not with everything that's been going on.

In the meeting of my Computer Systems Organization lab class for the twelfth week of the third term, we finally started working on counters after having discussed them in class.

I gave them the task of coming up with a state diagram with eight states and three bits that is not sequential, the only conditions being that only one bit should be changed from one state to the other, that all the possible states (two raised to the number of bits, which totals eight) should be used, and that the “last” state should “flow” naturally back into the first.

There are already three possible second states starting from three zeroes, so I told the groups that their diagrams should not be identical, which was intended to discourage parasitic behavior between groups.

From the state diagram they had to come up with the state table (applying the current and the next states) using T flip-flops and another one using a JK flip-flops. Next was of course the K-map for determining how the present states or outputs of the flip-flops could be used to create the necessary inputs for the next state.

That is, they had to use the K-map if the relationships between the present states and the inputs were not self-evident from the table. Besides, analysis of the table only worked best for the sequential counters, and this was non-sequential.

At the same time that some of the group members were making the tables and schematic diagrams, the rest were still working on completing some of their previous experiments, and had them checked in the first half of the period.

Unlike the previous experiments though, here I just listed down the outputs of the tables and signed them, instead of telling them whether their circuits were correct. This is because it seems no one got any of the complementary flip-flop outputs correctly, or bothered to troubleshoot the gates that compose the flip-flop.

Some groups also made the mistake of disconnecting their clock pulse sub-circuit, which they still had to use in the succeeding tasks, so they had to build them again, starting from the 555-chip check circuit.

Session 1061 removed the clock pulse circuit prematurely. Class dismissed.