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 meeting of my Computer Circuit Fundamentals lecture class for the sixth week of the second term, we continued with their ninth exercise, which is to accept two one digit numbers (with error checking) and to multiply the numbers and to display the one to two digit results, whichever it may be.

The funny thing was that it was supposed to show them how to display numbers of more than one digit, or whose tens digit is more than one, for which there already is a smaple program, but they had more difficulty with displaying and processing their input.

I gave them the hint that first they are supposed to receive the initial character from the keyboard, then to verify if it is valid, then to display it on the screen, then to convert it to the numeric value and finally to store it in a temporary variable.

For one thing the students were a bit confused as to what to do first, and when to convert to numeric and when to convert from numeric (which have different commands). When they converted first before displaying to the screen, they got the smiley face.

Another problem was that if they had a value in the most frequently used register before calling another interrupt, the value is sometimes overwritten, and whatever value they had there, if they did not store it somewhere temporarily, is now lost.

Therefore if they tried to access that data assuming the value was still the same one they used in the register before calling the interrupt, it would come up with a different result which is erroneous, and had to be reverse engineered to find out where it was wrong. This time, none of the students or groups had it in mind to use the push and pop instructions of the stack, which they had used too much before.

Some groups also did not use the standard comparison label jumping instructions to check values, such as jump equal, jump above or jump below, but they used either jump zero or jump signed.

Lastly, some groups were still confused with how to use the division (and multiplication) instructions that required only one variable, with the second variable being again the most used register.

Session 1363 is not used to copy and paste program creation. Class dismissed.