Taking ECE 391 Without Having Taken ECE 190

Notes prepared by Prof. S. Lumetta

There are a few concepts and skills that one learns in ECE 190 and that are expected from students who want to enroll in ECE 391 to have. Some of these can be obtained in other classes, but several have to be learned independently.

Can be obtained in other classes:

• Programming Experience. Students in ECE 190 typically write programs with O(500) lines of C code. The major projects involves things like an LC-3 simulator, and iterative deepening search to drive a number puzzle GUI (GUI provided), and a LC-3 assembler. If you have never written programs with more than ten or a hundred lines of code, you will be at disadvantage. It’s hard to compare directly with other languages, but CS 225 seems like an adequate preparation for programming experience.
• Basic Computer Organization. The LC-3 is described and examined at a fairly high level in ECE 190. The more detailed designs in 290 should be more than adequate, even if you have not taken ECE 190.

Will have to be learned independently:

• Calling Conventions and Stack Frames. In ECE 190, we discuss in some detail how stack frames for functions are created, used, and torn down with the LC-3, as well as discussing the meaning and specifics of the LC-3 calling convention and how it is used to map C functions to assembly code. You will not see this type of information in any of the classes that you might have taken before ECE 391, so you are probably going to need to read Patt and Patel (ECE 190 book) and/or look at assembly code generated by a compiler (gcc –S).
• C to Assembly Translation. Students in ECE 190 should have a reasonable good grasp of the relationship between C code and the assembly code produced by compiling that code. They have also been exposed to the implementations of various more advanced language and library constructs (e.g. simple memory management, virtual function tables), but have not written implementations themselves. As with the previous item, there is no exposure to these concepts in other classes that you might have taken before (exception is ECE 411 and CS 426).
• Assembly Programming. Students first learn LC-3 machine code and LC-3 assembly code, and write a machine problem at each level (O(100) lines, so a little smaller than the C experience). As working with device interfaces requires fairly careful control of data movement, students with no assembly experience will be at disadvantage. The only other class in which students get assembly exposure is ECE 390 (the old ECE 291). ECE 190 students have already seen one assembly language, but they are all reasonably similar.

So what’s the bottom line? If you haven’t taken ECE 190 but want to enroll in ECE 391, you’ll probably want to go to the library and read through the relevant sections of Patt and Patel (ECE 190 book). You may want to try your hand at using some of the things mentioned above. You can get assignments and pointers from the ECE 190 website.