Schedule

After a quick recap of course logistics, we dive right into the RISC-V ISA and the Mango Pi MQ-Pro SBC we'll be using this quarter. Introduce instructions for arithmetic and logical operations.

Readings:

• For background, review our guides on electricity, binary/hexadecimal numbers, and the unix command line.
• Bookmark this collection of unix video tutorials that were prepared for CS107 students. These videos cover basic concepts, common utilities, development tools, and productivity features.
• An interactive tour of Mango Pi board
• The Ripes RISC-V simulator demoed in lecture.
• Our one-page guide to RISC-V.
• A "for fun" diversion: Steven Wolfram's blog post Untangling the Tale of Ada Lovelace traces the work of Charles Babbage and Lady Ada Lovelace to develop the concept of a general-purpose computer.

More RISC-V assembly: control flow using branch/jump, load and store instructions, instruction encoding and decoding. Tools to build and execute an assembly program. GPIO peripheral control via memory-mapped I/O.

Readings:

• Here is a link to the Ripes simulator demoed in lecture.
• If you have a printout of the one-page guide to RISC-V, bring it along!
• From D1-H User Manual: Ch9.7 GPIO
• Course guides on Meet your GPIO pins and Programming your GPIO pins
• Enjoy Danny Cohen's article Holy Wars and a Plea for Peace on the history of little-endian vs. big-endian.

Moving up from assembly to C. Implementation of C expressions and control structures.

Readings:

• Brush up on C basics (syntax, data types, operators, control structures) via your favorite C reference; sections 1-2 of Nick Parlante's EssentialC; or chapters 1, 2, and 3 of K&R. Skip content on I/O and standard libraries (we are bare metal!)
• Read Dennis Ritchie's account of the history of C
• Try out the Compiler Explorer demoed in lecture
• Read our guides on make and gcc

Memory, addresses, and pointers. Address arithmetic, layout of arrays and structures. Typecast and volatile.

Readings:

• Review EssentialC chapters 3 and 6 (postpone heap and memory management for later) or K&R 5.1-5.4.
• C volatile can be subtle and tricky. See GeeksForGeeks advice on correct use and John Regehr's blog on what NOT to do with volatile

How functions are implemented. Control flow: call and return. Parameter passing, local variables, return value. Coordination on use of registers. Runtime stack management.

Readings:

• Read up on C functions (Chapter 4 in K&R, or Section 4 in Essential C).

Using gpio pins to transmit bits/signals, UART hardware peripheral, Ascii character set, C-strings. Strategies for testing and debuggging.

Readings:

• Review this excellent tutorial on serial communication from Sparkfun.
• Use your C reference to read up characters, C-strings, and output functions (putc,puts,printf) (Sections 1.5, 1.6, 1.9, 5.5, 6, 7 in K&R; or Section 3 in EssentialC). C-strings are primitive compared to Java/C++ strings; take note of the manual effort required to use and pitfalls to avoid.
• Helpful overview with examples: C Strings are Weird: A Practice Guide
• Read our course guides on testing and gdb debugger.
• Historical diversion: Poul-Henning Kamp's essay on The Most Expensive One-byte Mistake. Did Ken, Dennis, and Brian choose wrong with NUL-terminated text strings?
• Summer reading: The Victorian Internet by Tom Standage is a faascinating account of the world shift from invention of the telegraph and early digital communication.

Module design, makefiles, build process, preprocessor, linking, symbol resolution and relocation, program start sequence.

Readings:

• Our guide to binutils
• Anatomy of a simple linker script example from ld documentation
• Longer tutorial on bare-metal RISC-V build, thanks to Lucas Fryzek
• Go deeper: David Welch's very thorough articles on baremetal programming and bss data.

Stack allocation: stack frames, local variables, backtrace. Dynamic allocation: implementing a heap allocator. Runtime detection of memory errors.

Readings:

• Read our overview of stack frames
• Review dynamic memory allocation (malloc/free in C) and the operation of the heap (K&R 5.6-5.9 or Essential C Section 6). Compare and contrast stack versus heap allocation. Why do we need both?

We're around the halfway point! We will use this lecture to catch-up/expand on lecture content covered lightly on first pass, and discuss how to further your mastery of C.

Readings:

• Google style guide for C/C++ code: https://google.github.io/styleguide/cppguide.html
• Read code! Our code, your code, other published code,… Some selected projects to browse:
  • https://github.com/dwelch67/raspberrypi, David Welch baremetal examples
  • https://opensource.apple.com, Apple OpenSource
  • https://directory.fsf.org/wiki/GNU, Free Software Foundation (GNU)
  • https://musl.libc.org, Musl C library
• The masters share their best practices in the book "Beautiful Code: Leading Programmers Explain How They Think" https://www.amazon.com/dp/0596510047

Prof. Chris Gregg will lead a lecture on all things keyboard: the venerable P2S/2 protocol plus bonus excursions into Midi protocol and controlling an old-school typewriter!

Readings:

• Read Adam Chapweske's overview of the PS/2 protocol for keyboards and mice.
• Neat video from Ben Eater demonstrating how to read PS/2 scancode via breadboard wizardry. He does it all in hardware, thankfully easier for us in software!