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 first class of my Computer Circuit Fundamentals lecture for the ninth week of the first term, I taught the students about how to read and set the computer’s system clock, and how to multiply two numbers one of which is thirty two bits, when only sixteen bit operations on such are allowed.

First, I showed them how the computer uses the all purpose registers to count the number of one-eighteenth second ticks that have elapsed since midnight, which can then be translated to hours, minutes, seconds and milliseconds (approximately fifty five each).

That means that the value has to be divided by a thousand to find out the number of seconds, by sixty thousand to find the number of minutes, and by three million six hundred thousand to find the number of hours.

And since the registers can only accommodate values up to sixteen raised to four minus one (or 65,535) the value really needs to be divided in that sequence to be able to get the number of hours, which will then just use a divisor of sixty from the quotient of the second to the last operation.

As for multiplying the thirty two bit number by 55 in the first place, they had to perform the operation on the lower sixteen bits of the number first (after, of course, moving the value since the register where it is originally stored is going to be used for the multiplication) and keep the higher sixteen bits of the result somewhere (which they took literally, creating a variable named “somewhere”).

Then they perform the same operation on the higher sixteen bits, and add the higher sixteen bits from earlier. I remember when as a student this was given to us as an exercise, and I’m just giving it to my students now, and they have to incorporate it in more complicated exercises.

The two exercises I gave them were, first, to read the display the system clock up to seconds (quelling complaints about displaying milliseconds when they themselves brought it up), and the second, to display the time elapsed between the first and second press of the enter key, based on a game they saw on the ASCII code table site.

Session 1391 dissects games. Class dismissed.