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https://github.com/zrthxn/8puter

Homebrew 8-bit computer project
https://github.com/zrthxn/8puter

6502 hardware-designs sbcomputers

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Homebrew 8-bit computer project

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# 8puter



This is a Homebrew 8-bit computer project, using mostly simple modern parts.

Based on the legendary MOS6502 processor, we are using the modern CMOS version made by WDC. Basically an exercise in computer architechture. I plan to get this manufactured into a PCB and assemble myself into a working computer. 



Please feel free to leave reviews/sanity checks from people who have done this sort of thing before, or know something about this, in the [issues](/issues).  



## Preview



Here is a picture of a 3D model of the completed PCB.



  






// 

Schematic / 

Bill of Materials 

//




## My Goals



The main thing I want to be able to do with this SBC is to program it with itself. This means having some way to input text from a keyboard and display it to some kind of screen/output device, and I've chosen a VGA monitor for this. I'm not trying to keep this compatible with the ROMs/BIOSs or code of old but I want to be able to write my own, preferably on the machine itself. 

Also, I dont want to use discrete logic for everything since I have some experience with trying to make that work. I'm also not necessarily using all DIP chips because of lack space, and going SMD isnt that much of a problem.



To store programs on a sort of "disk", I thought I need to add some sort of serial interface which can talk to a microSD card, such that the computer can use it as storage. This is accomplished via SPI. 

The peripheral interface talks to a USB controller and *should* be able to use a USB keyboard as input device. This idea was taken from the schematic of the [SBC dev board that WDC sells](https://wdc65xx.com/Single-Board-Computers/w65c02sxb/).



The video signal is being generated by a microcontroller because I thought that's probably the easiest way to get it working without worrying about a lot of VGA signal timing. This MCU is fast enough to generate a 640x480 screen and has enough memory to store the framebuffer and its the only *cheat* I've used. Some more details are in my schematic



### Main Parts



**uProcessor:** W65C02S  

**ROM and RAM:** AT28C256 and AS6C62256, both 32K  

**VIA:** W65C22  

**USB I/f:** FT245RL  

**Video:** PIC32MX270 uController



## Manufacturing



So after quite a while, I have finally got this PCB manufactured and it came out better than I had imagined.

I was having trouble finding a local PCB maker who had the right capabilities and would manufacture this board at a small scale. 

Then I found Robu.in and their manufacturing service. I'm not sure if they've been doing this for a while but I never knew about them.



The board files are ready to send to a manufacturer of your choice as they are. You can find the gerbers in a ZIP and just fire them off. 

I recommend Robu.in if you're in India. Otherwise I'd recommend PCBWay.com






See the [Releases](https://github.com/zrthxn/8puter/releases) for updates.



## Resources



Some great resources I found for this project, including those from people who have done this sort of thing before.



- [Ben Eater's Excellent Videos](https://www.youtube.com/watch?v=LnzuMJLZRdU&list=PLowKtXNTBypFbtuVMUVXNR0z1mu7dp7eH)

- [George Foot's videos](https://www.youtube.com/watch?v=EC1Ous1zT5w&list=PLWKtKD_FaUF6IsFc1maERpOwWM2hrOM3b)

- [forum.6502.org](http://forum.6502.org/)

- [WDC's own SBC board schematic](https://wdc65xx.com/Single-Board-Computers/w65c02sxb/)

- [6052 Primer](http://wilsonminesco.com/6502primer) on how to get started building your own, especially the [address decode](http://wilsonminesco.com/6502primer/addr_decoding.html) section

- [6502.org: Homebuilt Projects](http://www.6502.org/homebuilt)

- [This guy's breadboard computer](https://www.youtube.com/watch?v=sdFXc0Rkpvc&list=PLdGm_pyUmoII9D16mzw-XsJjHKi3f1kqT) which is based on the (later) 65816 processor, but has some great ideas.