Kudos and many, many thanks from X65

[smokku]

I would like to hereby thank @rumbledethumps for the awesome Picocomputer project.
Your videos on YT inspired me to finally get to work and build my own 8-bit machine.

The first design was based on the Neo6502 idea of multiplexing the full 6502 bus to an RP MCU and running the RP6502-RIA firmware on it.

I run the 65C816 CPU, so the RP MCU also serves as a bridge to 16 MB of PSRAM memory.

Similarly, I have a second RP MCU generating video over DVI-D output.
The design of the chip is heavily inspired by Atari ANTIC and Commodore TED.
It sports a 256-color palette, runs a display list serving modelines of text, bitmap graphics, HAM, and MODE7. It supports 8x Amiga-like sprites with a built-in multiplexer. This all runs on 4 overlaying layers - either a graphics or sprites layer.

Moving to RP2350B allowed me to compact these two functions into one chip.

The full DEV-board also has a Yamaha SD-1 sound synthesizer, a ROHM audio mixer, and ESP32 WiFi/BT.

The machine is called X65. It has its own webpage https://x65.zone/ and an online emulator with a few demos: https://x65.zone/emu/
The emulator also has native builds for Linux and Windows, downloadable from GitHub.

Part of the project is cc65-dbg, which allows debugging CA65/CC65-compiled programs using any debugger/emulator supporting the DAP protocol. Of course, the X65 emulator supports it.

I wrote it to aid the development of OS/816 - a multitasking operating system built on unique 65816 CPU features that I am writing for X65.

Testing the DEV-board revealed some crucial design issues, so I started this year by building an X65 Gen2 prototype.

It already performs better on a breadboard than the Gen1 one did on a PCB.

One of the changes introduced this year is removing the SD-1 synth chip and replacing it with a custom design based on yet another separate RP2350 MCU. You can hear the new chip performing live on the X65 YT channel: https://youtu.be/Um4VnszF-7s

Once again, many, many kudos and thanks to @rumbledethumps for creating and open-sourcing the Picocomputer 6502, and for an awesome YT series explaining how it works. 😀

Without this, there would be no X65…

[rumbledethumps]

Fantastic! Several people have asked about the 816. Now I can send them somewhere.

Looks like you gave up the xcvr idea after disappointing performance. Now you're back to dual Picos. Or is that three I see? Pi Picos have become the Bondo of retro computing.

[smokku]

There are three:

• bridge
• graphics chip
• sound chip

Pi Picos have become the Bondo of retro computing.

🤣