punch

Punch is a virtual computer system that draws inspiration from iconic computing platforms such as the Commodore 64, Amiga 500, and Atari ST. Notable features include:

• Utilization of the MC6809 CPU using the MC6809 library
• A total of 16MB of video RAM, 64KB directly accessible by the CPU
• Screen resolution of 320x200 pixels, refresh rate of 60Hz
• Blitter chip for fast graphics processing
• Programmable using either MC6809 assembly or the Squirrel Programming Language

Table of Contents

• Memory Model
• Blitter

Screenshots

Startup screen

Debug screen

Memory Map

Addressable by MC6809 and Blitter

work in progress

• $000-$0ff direct page (default after reset)
• $100-$3ff available ram and system stack pointer (768 bytes)
• $0400-$0fff input/output area
  • $400-$4ff blitter surface descriptors (16 in total, 16 bytes each)
    • $4x0-$4x1: x position (16 bit signed)
    • $4x2-$4x3: y position (16 bit signed)
    • $4x4-$4x5: w width (16 bit unsigned)
    • $4x6-$4x7: h height (16 bit unsigned)
    • $4x8-$4xb: base address of surface data ($8 will always contain $00)
    • $4xc: flags_0
    • $4xd: flags_1
    • $4xe: flags_2
    • $4xf: index ("sprite pointer")
  • $500-$5ff blitter surface color tables (16) for 1, 2 and 4 bit color modes
  • $600-$7ff sound
  • $800-$8ff core
    • $800 status register
    • $801 control register
  • $900-$9ff keyboard
  • $a00-$aff timer
  • $b00-$bff commander (scripting engine)
  • $c00-$dff reserved area
  • $e00-$eff blitter
    • $e00 status register (unused)
    • $e01 control register
      • write 0b00000001: blit source to destination surface
      • write 0b00000010: tile blit source/dest/tile
      • write 0b00000100: clear destination surface with drawing color
      • write 0b00001000: pset
      • write 0b00010000: line
      • write 0b00100000: rectangle
      • write 0b01000000: solid rectangle
    • $e02 source surface pointer (lowest nibble only)
    • $e03 destination surface pointer (lowest nibble only)
    • $e04 tile surface pointer (lowest nibble)
    • $e05 drawing color
    • $e08-$e09 x0 for drawing operations (16 bit signed)
    • $e0a-$e0b y0 for drawing operations (16 bit signed)
    • $e0c-$e0d x1 for drawing operations (16 bit signed)
    • $e0e-$e0f y1 for drawing operations (16 bit signed)
    • $e10-$e13 vram peek base address (24 bits, $e10 always #$00)
    • $e18 added alpha value during blits
  • $f00-$fff vram peek
• $1000-$fbff 59kb ram ($fc00 is initial usp)
• $fc00-$ffff 1kb kernel + vectors

Addressable by Blitter only

• $010000-$ffffff available vram (16.320kb) of which:
• $f00000-$f3e7ff default framebuffer vram (256.000 bytes)
• $f3e800 draw color, 32 bit, stored in vram

Building with CMake

Create a build directory in the source tree mkdir build, run cmake .. from that directory and run make. Alternatively do mkdir Debug, run cmake -DCMAKE_BUILD_TYPE=Debug .. from that directory and run make.

Below some more OS specific intructions on how to prepare the build environment.

MacOS specific

• Install Xcode from App Store
• When it asks to install command line tools, do that
• Install Homebrew
• From the Homebrew command line, install cmake and SDL2 libraries

Ubuntu / Debian specific

To be done

Windows specific

To be done

Websites and projects of interest

• CCS64 - A Commodore 64 Emulator by Per Håkan Sundell.
• Commander X16 - The Commander X16 is a modern 8-bit computer currently in active development. It is the brainchild of David "the 8 Bit Guy" Murray.
• Commander X16 emulator - Software version of Commander X16.
• freeverb - Free, studio-quality reverb SOURCE CODE in the public domain
• Hatari - Hatari is an Atari ST/STE/TT/Falcon emulator.
• lib65ce02 - CSG65CE02 emulator written in C.
• MC6809 - MC6809 cpu emulator written in C++.
• Mega65 - The 21st century realization of the C65 heritage.
• Moira - Motorola 68000 cpu emulator written in C++ by Dirk W. Hoffmann.
• reSID - ReSID is a Commodore 6581 and 8580 Sound Interface Device emulator by Dag Lem.
• SDL Simple DirectMedia Layer - A cross-platform development library by Sam Lantinga designed to provide low level access to audio, keyboard, mouse, joystick, and graphics hardware.
• Squirrel - Squirrel is a high level imperative, object-oriented programming language, designed to be a light-weight scripting language that fits in the size, memory bandwidth, and real-time requirements of applications like video games.
• stb - single-file public domain (or MIT licensed) libraries for C/C++
• TIC-80 - TIC-80 is a free and open source fantasy computer for making, playing and sharing tiny games.
• vAmiga - An Amiga 500, 1000, or 2000 on your Apple Macintosh by Dirk W. Hoffmann.
• vasm - A portable and retargetable assembler.
• VICE - The Versatile Commodore Emulator.
• VirtualC64 - A Commodore 64 on your Apple Macintosh by Dirk W. Hoffmann.
• visual6502 - Visual Transistor-level Simulation of the 6502 CPU and other chips.

MIT License

Copyright (c) 2023-2024 elmerucr

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.