lc3

LC-3 VM in Go

An LC-3 VM implementation as described at https://www.jmeiners.com/lc3-vm.

Features

Besides the obvious (running LC-3 programs):

• uses alternate buffer to preserve terminal state;
• hides cursor for a more immersive gaming experience :-)
• graceful shutdown by capturing Ctrl-C;
• partial integration testing by running 10 x 1KB, automatically generated images (using random combinations of ADD, AND, LD, LDR, NOT, LDI and LEA opcodes) and verifying the CPU registers at the end (TODO: verify memory too);
• loading images at the address specified in the object file, NOT hardcoding PC to 0x3000.

And just for the fun, since I control the VM anyway ¯\_(ツ)_/¯ a bit of hacking:

• allow using arrow keys for input (convert them transparently to WASM);
• output nicer box for 2048 using DEC Line Drawing.

Useful

Resources:

• https://www.jmeiners.com/lc3-vm/
• https://www.jmeiners.com/lc3-vm/supplies/lc3-isa.pdf
• https://students.cs.byu.edu/~cs345ta/labs/P4-Virtual%20Memory.html
• https://en.wikipedia.org/wiki/Little_Computer_3
• https://www.andreinc.net/2021/12/01/writing-a-simple-vm-in-less-than-125-lines-of-c

Tools:

• https://wchargin.com/lc3web/
• https://www.exploringbinary.com/twos-complement-converter/