#1591: Major OS updates, AirPods firmware update, non-Google accounts in Gmail app, Time Sensitive notifications, Apple Watch Web browserĮmulation, Virtualization, and Rosetta 2: A Blend of Old, New, and Yet To Come.
#CHASM EMULATOR UPDATE#
#1592: Life with HomeKit, notification summaries, Music/iTunes Store oddity, inadvertent Mail deletion, iOS update error, holiday hiatus.
#1593: Wordle, vinyl skins for Apple laptops, Apple Music Voice Plan, ad hoc Wi-Fi networks.
#1594: iOS 15.2.1, AirTag stalking, CES Tech Trends for 2022.
#1595: Replacing the Time Capsule, AT&T and Verizon 5G coverage expands, is iOS 15's Focus overkill?.
This lets us do fun things like modify the sequence of bytes used to draw to the screen, which creates glitchy and unpredictable results! For example, in breakout.chasm we can modify the amount of bytes to be drawn, from 1 to 12, for lines 6 (the vertical bars), 46 (the paddle), and 48 (the ball). We can also modify these instructions and re-assemble the game. While still a bit difficult to grasp, this is significantly easier than trying to sift through the bytecode.
DRW V10, V11, 1 => At position X, Y, using the numbers found in registers V10 (0) and V11 (6), draw a 1-byte sprite starting at memory address in register I.
LD I, 780 => Load the address of a sprite at memory address 780 into register I.
Here we see a list of instructions, written out using the typical opcode mnemonics for CHIP-8, for example: Here is an example of the output of the disassembler for the Breakout game found in roms/. chasm file, which you can peruse at your leisure in your IDE of choice. To get a better sense of the instructions used to build CHIP-8 games, I hacked together a (still pretty clunky) disassembler and assembler (see Usage above for running them). In terms of graphics, the emulator draws sprites a 64x32 pixel buffer, which has been scaled here by a factor of 10.Īudio consists of a single beep. For examples, with the pong.ch8 ROM, the vertical movement of the left paddle can be controlled with 1 and Q, and that of the right paddle with 4 and R. The original CHIP-8 keyboard had a 16-key keypad, which has been mapped to the following: 1Įach game has a different mapping, which often requires experimenting to find out the proper keys. For a list of opcodes, see this table on Wikipedia. The base CHIP-8 has 35 instructions (with the upgraded Super CHIP-8 adding 10 more), which include basic operations such as math, control flow, and graphics. Once a game's ROM has been loaded (typically starting at address 0x200), the program counter increments through memory two bytes at a time, fetching the instruction or opcode at that address.
a simple stack for storing addresses during calls to sub-routines.
a program counter holding the next instruction to be decoded.
16 8-bit general purpose registers for fast storage, arithmetic operations, etc.
4096 bytes of memory (of which the first 512 bytes were normally reserved for the virtual machine).
The architecture for the CHIP-8 virtual machine is rather simple: Note: There aren't yet any checks for proper file extensions! CHIP-8 Structure target/release/chip8rs /roms/pong.chasm -a chasm file, creating a new file (named _a.ch8) in the same directory: target/release/chip8rs /roms/pong.ch8 -d Assembler chasm file in the same directory as the source: Using the -d flag, you can disassemble a ROM into the CHIP-8 assembly language, which will create a new. target/release/chip8rs /roms/pong.ch8 Disassembler Usage EmulatorĪ couple games have been included in the /roms directory.