A 6502-Based Single Board Computer

[@vanhetgoor]

I like it, there much inspiration from many to been seen here. I have a Grant Searle's PCB for a 6502 computer. Here and there you can see others that all have added one thing or another, it would be nice if someone would add up all extra's and combine it to the ultimate 6502 single board computer.

[@davethetaswegian]

Gives me warm fuzzy nostalgic feelings. My first computer was an OSI Challenger 1P MF. I still have it in storage somewhere.

[@jefftranter]

My first computer was an OSI Superboard II, essentially the same but just a board without case or power supply.

[@CCS1024]

Great project. Jeff has recently ported wozmon for his SBC.

[@estebanvillalobos2303]

I built one, it's quite full featured. thanks for making it.

[@harperlarry49]

Very cool. Brings back a lot of memories. My first computer was designed by a JPL engineer and was based on the Intel 8085 cpu. Everything was hand wire wrapped. Thanks for sharing.

[@jefftranter]

My prototype ran on a breadboard (actually several) but my 68000 board was initially wirewrapped.

[@harperlarry49]

@@jefftranter I have been away from that part of the hobby for 30 years. Now I play with Rasp Pi and Arduino. People still do wire wrapping? Cool.

[@3vi1J]

For a split second, I didn't notice that was a C64 mini @0:30, and I was like "Wait... did they make an Apple for Andre The Giant?" Really cool projects, Jeff - keep making these interesting videos!

[@spotterinc.engineering5207]

Great project. I have a soft spot for 6502 computers as I used many Apple II's for projects back in the day. A very versatile system - but it would be cool to have a simple SD based file system too.

[@jefftranter]

I've been experimenting with a serial to USB flash module: www.hobbytronics.co.uk/usb-host-flash-drive

[@cocusar]

I also fancy the easyEDA web editor, and I did a retro z180 board on it. pretty cool!

[@gordonreeder3451]

Nice. I actually still have an OSI Superboard 2. I also have some Moto chip, including a 68008 CPU and a couple of DUARTS. That would be a fun project.

[@josefont11]

that is real nice! thank you.

[@StochasticJeff]

Fwiw, first thing I always stuff into my ROM is an S-record loader. Makes it relatively painless to get new code onto the target w/o having to play silly buggers with eproms :)

[@PWingert1966]

I got an NMI looking at the Hex Dump!

[@wadereynoldsgm]

Cool project! Thanks for sharing

[@jeffnay6502]

Hey Jeff, awesome video. I have recently purchased Ben Eaters 6502 bread board computer project. However I wanted to be able to add a keypad and 6 SSDs so that I could use it, similar to the KIM-1 computer. I have just created a small, although uncompleted series on Keypad integration, using an 8051 to simplify the learning process. However looking at the KIM-1 schematic, and the 74145, it looks like I may have taken a slight left turn at Albuquerque. Although it has been a good learning lesson in keypad scanning and multiplexing. I do have one question on the KIM-1 schematic, as I am not an EE or even close and I am also, not a coder either. It is easy to see how the 74145 is not only multiplexing the 6 SSD it is also multiplexing the 4 rows on the keypad. My question is, what port on the PIA (U2) is the key that is pressed detected on? and is that port being used bidirectionally? To send out the 7 segment code as well as to receive the key pressed signals? I do have the KIM-1 assembly language program documentation, and I am trying to understand parts of it as I go along. I was really impressed by the monitor program that you displayed on your 6502 SBC. Awesome work !!!

[@jefftranter]

It would take me some time to study the KIM-1 keypad circuitry and code. I'd refer you to the KIM-1 User Manual which can be found on the internet, and this web page which appears to have some good info: www.baltissen.org/newhtm/kim.htm

[@scharkalvin]

Could also use a 27256 32k rom, or even a 27513 rom which is bank selectable to 4 16k banks.

[@jefftranter]

Yes, but with a 64K address space, 32K RAM, 32K ROM, would need to reserve some of the address space for the peripherals.

[@scharkalvin]

@@jefftranter Yes some of either the rom or ram space would need to be reserved. If enough decoding logic was provided, this could be as little as 512 bytes for the I/O chips you have used.

[@jefftranter]

@@scharkalvin I purposely tried to keep the chip count low and avoid using PALs or PLDs, which meant only simple address decoding. It would be nice to have more ROM.

[@scharkalvin]

@@jefftranter True. The 27513 eprom is a 4 bank 16k per bank part. With little added circuity and some code, it could house 4 different systems (basic, assembler, editor, monitor). Switching between each bank can be done in various ways such as having the switch routine in all banks, or by moving it into ram first. These parts aren't that common, but are available. There was also a 1 mega bit version as well.(8 banks of 16k IIRC)

[@JacGoudsmit]

Nice computer! Any plans on adding display hardware? You should add those URLs to the video description so people can click on them.

[@jefftranter]

Good suggestion - I added them.

[@myCloudWatcher]

Sd Chip would help a lot. Not hard to do a slow interface. Great work. What is the "general" cost of the build?

[@jefftranter]

I'd estimate about US$30 to $40 for the parts and PCB, less if you have some parts on hand or buy them in larger quantities.

[@StochasticJeff]

Links? A project blog? A git repo? If those boards can be fab'd so inexpensively, could I buy one? Bc I have all those parts in my salvage box.

[@estebanvillalobos2303]

Too bad you’re not perceptivejeff….

[@robertmccully2792]

How about a book on basic code use?

[@jefftranter]

A long list of 6502 books is here, some of which are available on-line: www.6502.org/books I recommmend 6502 Assembly Language Programming by Leventhal

[@IndellableHatesHandles]

The 6502 stack is extremely small, so how does cc65 handle most variables in C being allocated on the stack? This would be very useful to know as a programmer.

[@mr1enrollment]

consider Forth for this project

[@jefftranter]

I ported FIG Forth to a similar board: github.com/jefftranter/6502/tree/master/asm/fig-forth

[@mr1enrollment]

@@jefftranter LOL goodman

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