Community-Built Unnamed 1970's Video Game Console-Compatible System (WIP)

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Al_Nafuur

I am currently working on a new project which is in an early WIP/PoC phase (I even haven't come up with a name for the project). Proposals for a project name can be found here

 

The story behind this project is that I never liked the approach of the retron77. I always thought that it can be done better. When Atari announced the 2600+ with the same "wrong" approach I decided to test if my idea of doing a better device is feasible.

 

For my testing I use a Raspberry Pi 3B+ connected to a breadboard, but something similar should be possible with the CPUs used in the Retron77 or the 2600+. I have developed a special driver for Stella to connect the cartridge to the CPUs I/O and emulate a 2600 directly using the cartridge without dumping it.

 

If the driver handles the communication and the timings with the cartridge exactly like a real 2600 would do, a 100% of all bankings (even future bankings) and cartridges will work on this setup.

 

@Thomas Jentzsch, @MarcoJ and @DirtyHairy have supported me with ideas to improve the driver. Currently we are at about 85% of the emulation speed.

 

Current status is:

    Every std. banking cartridge seems to work (2K, 4K, F8, F6 tested)
    It seems I don't have a cartridge with SC-RAM to test.
    Decathlon cartridge (FE banking) still doesn't work (Stella debugger shows that the bank doesn't switch on a JSR)
    PlusCart seems to be fully working (including exit and PlusROM functions. See compatibility list below)
    GameLine cartridge shows briefly the intro message and then crashes or starts to puls dial. I think it might be an voltage issue here, because the Raspberry Pi shows a "Low Voltage" warning
    SuperCharger doesn't work
    I don't have a DPC+ or CDFJ cart to test.

 

Here is a compatibility list for all bankings tested mostly on the PlusCart, because I don't have the real cartridges:

https://forums.atariage.com/topic/354860-compatibility-list-for-all-bankings/

 

Software/hardware list for the breadboard setup:

    Raspberry Pi 3B+
    Pi OS with VS-Code and the SDL2 development libs
    The latest code from the Stella GIT repository.
    One 8-bit Logic Level Shifter (SN74LVC245AN) (~ $1.50)
    2600 cartridge port connector
    A breadboard
    Wires

 

How to connect the components:

https://forums.atariage.com/topic/354887-setting-up-the-unnamed-1970s-console/

 

Setting up the Raspberry Pi development environment:
https://forums.atariage.com/topic/354887-setting-up-the-unnamed-1970s-console/?do=findComment&comment=5317255

 

@ZeroPage Homebrew's reveal video on Youtube:

killersquirel

I am really looking forward to this. Is there any updates on the progress?

Al_Nafuur

Some things have to be fixed here, but this is basically how I would setup the system with a MAX-II as BIA (Bus Interface Adapter) and also for doing the IO part of RIOT and TIA.
 
The PiCLCK (GPIO4) is used as input clock for the MAX-II, so I had to move the data and address lines to GPIO5 to GPIO25. Unfortunately GPIO24 to 27 is used for flashing the MAX-II via the Pi, so I added jumpers to connect these double used lines during flashing (I hop this doesn't interfere with the other IO lines of the MAX-II)

Al_Nafuur

First PCB layout of the Prototype board (V1)


Al_Nafuur

this is the schematics. Does anyone sees any issues with it?

Andrew Davie


Andrew Davie

Perhaps put some copyright notices and/or licensing/use requirements on future images/posts?

Al_Nafuur

Quote from: Andrew Davie on 09 Aug 2024, 11:45 AMPerhaps put some copyright notices and/or licensing/use requirements on future images/posts?
Good point! The boards are in an early state, but even in this state the license should be included.

I thought of using the TAPR open hardware license:
https://files.tapr.org/OHL/TAPR_Open_Hardware_License_v1.0.txt



Al_Nafuur

I have made a KiCAD footprint for the EPM240 mini board to be "overlayed" over the EPM240. Now the test board can be populated with a smd EPM240 or with the breakout board. The pin headers can be used for testing.




Al_Nafuur

Money has been spend and prototype boards have been ordered:


killersquirel

This is awesome news. I am looking forward to hearing more about this project.

Al_Nafuur

Quote from: killersquirel on 05 Sep 2024, 11:14 AMThis is awesome news. I am looking forward to hearing more about this project.
There is more information at the AtariAge Club for the hardware/stellaRT

https://forums.atariage.com/clubs/88-stellart/