# Uxn A stack-based VM, written in ANSI C. ## Build ``` cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn ``` ## Assembly Syntax - `;variable`, a named address(zero-page) - `:label`, a named address - `.pointer`, a pointer to a label - `@0010`, a position in the program ``` < conditionals > .there ( 0a 05 GTH ) JMC :here < when not equal > ee BRK :there < when is equal > ff BRK ``` ## Mission ### Assembler - Crash on missing label - Catch overflow/underflow - Constants - Jumps should be relative ### CPU - Pointers/Literals - A Three-Way Decision Routine(http://www.6502.org/tutorials/compare_instructions.html) - Carry flag? - Print word to stdout - Draw pixel to screen - Detect mouse click - SDL Layer Emulator - Build PPU - Interrupts, vectors ### 16 Bit Missions - 16 bits addressing - jumping to subroutine should be relative - Implement addressing - Implement 16 bits operations ## Refs https://code.9front.org/hg/plan9front/file/a7f9946e238f/sys/src/games/nes/cpu.c http://www.w3group.de/stable_glossar.html http://www.emulator101.com/6502-addressing-modes.html http://forth.works/8f0c04f616b6c34496eb2141785b4454 https://justinmeiners.github.io/lc3-vm/