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Pugo Oric

This project implements a basic Oric computer emulator with graphics, sound, etc. All code is written from scratch.

It is my absolutely slowest project, just made out of love to programming and to my first computer.

Background

This is the result of a very long and low intensive hobby project I have worked on since 2009, which currently is 14 years.

The purpose was to develop an emulator of the first computer I ever got, as a Christmas gift some 40 years ago. The computer was an Oric 1, and it was fantastic back then!

There already is a brilliant emulator of Oric: Oricutron, which is more complete than this project ever likely will be. The purpose of my emulator project has been to learn more about how emulators work and to close the circle by learning more about the computer I got as a kid.

Building

The project should be possible to compile on Linux and macOS using CMake.

It can be built with local libraries as well as with vcpkg.

Dependencies

The following dependencies are required.

  • boost
  • sdl2
  • sdl2_image

If building with vcpkg the dependencies does not need not exist as system-wide packages, such as DEB or brew packages.

Compile with CMake using vcpkg

It is possible to build the emulator using the vcpkg dependency manager.

Prerequisites

This requires a working vcpkg installation.

The environment variable VCPKG_ROOT should point to the root of the vcpkg installation.

Install dependencies

The vcpkg.json file contains all the dependencies. To install them, do as follows.

$ vcpkg install
$ vcpkg integrate install

There is a predefined CMake preset for using vcpkg, use it as follows.

$ mkdir build
$ cd build
$ cmake --preset=vcpkg ..
$ make -j10

Compile with CMake with existing dependencies

This should typically be done like the following.

$ mkdir build
$ cd build
$ cmake ..
$ make -j10

Running

The program currently looks for ROM files from the ROMS directory in the project root, so you might want to run the program from there:

$ ./build/oric

Command line arguments

Run the emulator with flag -? (or --help) to see available parameters.

$ ./build/oric -?

Usage: oric [options]
Allowed options:
  --help                produce help message
  -m [ --monitor ]      start in monitor mode
  -a [ --atmos ]        use Atmos ROM
  -t [ --tape ] arg     Tape file to use

Control keys

The following control keys can alter the emulator behavior.

  • F4: Make snapshot (to RAM)
  • F5: Load snapshot (from RAM)
  • F10: Soft reset the emulator (NMI)
  • F12: Toggle warp mode (go as fast as possible).

Loading from tape image

To specify which tape TAP file to use, use the --tape or -t command line argument:

$ ./build/oric --tape taps/hunchbk.tap

To load a tape program from the emulator you can try the following.

CLOAD"

To speed up the loading time it is possible to toggle warp mode with F12.

Exiting

Since the emulator does not have any GUI with interaction at this point the best way is to simply close the window.

It is also possible to press ctrl-c in the terminal window where the emulator was started. On the first press of ctrl-c the emulator will enter the monitor mode. See the monitor section below for more information about the monitor. To exit for real, press ctrl-c a second time.

Monitor

You can at any time enter a small monitor mode by pressing ctrl-c.

The monitor has commands like the following.

Available monitor commands:

h              : help (showing this text)
g              : go (continue)
g <address>    : go to address and run
pc <address>   : set program counter to address
s [n]          : step one or possible n steps
ay             : print AY-3-8912 sound chip info
i              : print machine info
v              : print VIA (6522) info
d              : disassemble from PC
d <address> <n>: disassemble from address and n bytes ahead
m <address> <n>: dump memory from address and n bytes ahead
quiet          : prevent debug output at run time
debug          : show debug output at run time
sr, softreset  : soft reset oric

Timeline

As I work as a developer this has been a project I have gone back to for shorter stints when normal work for some reason have had less amount of coding. That means that this project has been extremely slow. But that has always been a wonderful thing! I have never felt any pressure to work on it and instead hacked on it by pure love.

The first thing I developed was naturally the MOS 6502 emulation. That took several years of now-and-then coding. Then after some delay the MOS 6522 VIA (IO) chip work started and took some more years. After that I added graphics support, keyboard emulation, tape loading and lastly sound.

The timeline is something like:

  • 2009: MOS 6502 CPU
  • 2014: MOS 6522 VIA
  • 2016: Graphics
  • 2017: Key input
  • 2020: Tape loading
  • 2023: AY3-8912 sound
  • 2024: Cycle bug fixing, new monitor, blink mode, snapshots

Contribution

Since this is a pet project I work on only when I like to and because I feel that I should implement all by myself I am reluctant to accept any contributions. But the licence is GPL v3, so feel free to fork it and do what you like as long as you follow that license.

License

All code is licensed with GPL v3.

Sweden, Linghem 2024, Anders Piniesjö