Updated: Apr 27, 2022
Back in January, I decided to start building a 65816 "PC." Up to that point, I had built a 6502 system with basic elements of a PC. The key elements of a 65816 PC that I would like to have:
Core processing (65816, ROM, RAM, Extended RAM)
As of this post, I have the hardware completed for most of the above, minus the joystick support, which is an easy add. Here's a quick run-through of the hardware so far:
Core Processing + Keyboard Support + Easy Expansion
I have completed my "motherboard" that hosts the 65816, ROM, RAM, Extended RAM, address decode logic, PS/2 keyboard input, a VIA, and ISA slots for physical connection of add-in boards (not following the ISA protocol though). Current specifications:
Form factor: ATX
CPU: 65816 at 14.16 MHz
Memory: 32 KB Basic RAM and 512 KB Extended RAM
ROM: 480 KB
Expansion: Seven expansion slots using ISA connectors
I'm using a simple add-in card that hosts a VIA with an Arduino Mega + USB host shield. I convert the USB mouse data to simple signals that are processed on the VIA.
I have developed a graphics card that supports 320x240x1B (RRRGGGBB). This card leverages dual-port SRAM for the full memory-mapped video, allowing independent writes from the 65816 and reads from the video output circuit.
I have developed a sound card that supports 16 channels of audio with onboard media storage (ROM + SD card). The sound card runs its own, dedicated 65816+ROM+RAM so that it can run independently from the main system 65816 (e.g., to play background music). This card evolved from the sound card I developed for my 6502 system. What is pictured in the video is the core of the sound card on a prototyping add-in card. The full sound card PCB is currently being manufactured.
I plan to build a simple add-in card with a pair of serial inputs into a VIA. This will be similar to what I did on my 6502 build.
For a historical perspective, or for more details on any of my build's elements, check out my posts on these topics:
Schematics and PCB design files (EasyEDA format) are available at rehsd/PC-65816: PC based on 65816 (github.com).
*Lots* of 65816 assembly work! See 65816 Assembly Coding Series.
And I'm out of expansion slots... :)