Undergrad level computer architecture course Is there a good online course that covers computer architecture at an undergrad level?

I just finished 8th grade. I know a bit about computer architecture and logic gates, but not a ton. I know the basics of single-variable calculus and linear algebra, and I program a decent amount, mainly in Python 3, though I have experience with versions of C (used for Arduino, for example). I have looked at Assembly code but never programmed in it. 

I'd like the course to be decently cheap, and it would be nice if it has a sense of legitimacy such that I have a shot at getting it to count for credit/go on my transcript.

Any recommendations would be appreciated. Thanks!
My go-to answer for this topic is Nand2Tetris.

There are 2 Coursera courses (Part I and Part II) that match the curriculum of the program. The first course does not require any programming background. Its focus is on computer architecture (logic gates, half-adders, full-adders, ALUs, RAM, ROM). The second focuses on a virtual machine and a compiler for a high-level, Java-like language (and thus does require some programming knowledge). The essence is that you understand every level of a computer from the NAND gate up to a "hello, world" program in a Java-like language.

In addition to the Coursera courses, there's a companion textbook and a full suite of software. The list of topics is below:


Boolean Logic
Boolean Arithmetic
Sequential Logic
Machine Language
Computer Architecture
Assembler
VM I: Stack Arithmetic
VM II: Program Control
High-Level Language
Compiler I: Syntax Analysis
Compiler II: Code Generation
Operating System


The course is typically a lower-division, one-semester, university course. The site contains a sample syllabus, which might help justify it being rewarded with some form of academic credit.