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 seventh week of the third term, I gave each group a chance to construct either an adder circuit, a subtracting circuit, a magnitude comparator or a decoder.

If I had five groups instead of four, I would have one make an encoder as well.

I also taught the students how to use light emitting diodes to be able to show the outputs of their circuits, since we have circuits with more than one output now, instead of having to use a voltmeter to look at the numeric voltage output to determine whether it is considered as high or low, which some students still see as confusing.

I tried to use switches for them to control the input, specifically the doorbell switches that we were supposed to use for the buzzers of the science and math quiz contest we had last January, but somehow it wasn’t working even though we connected it correctly to the five volts. I will have to try that out between classes to make it work properly.

Unfortunately it was only one group that was able to complete their circuit. This was the group that made the decoder. But even so, they were not able to make two out of the eight outputs light up. Maybe it was a wrong connection on that part, but it worked sufficiently for me to call the other groups from their own tasks and look at the output of the finished group.

They just used the old method of reconnecting the inputs (three for the case of the eight-output decoder) to either zero or five volts to determine the output, which is that only one of the eight light emitting diodes will turn on.

The problem for the other groups was the lack of chips, particularly the gates, that they needed to use for their circuit. So I had to reduce their task from four bits, down to three bits, then further down to two, but it was already too late in the period for them to restart everything from scratch.

I didn’t have to tell them that I would still be available for make up sessions in the lab as long as I don’t have a class and the lab is available.

Session 1015’s lacked chips. Class dismissed.