My home-brew 68K machine just recently reached the same level of completeness except for the particular BASIC implementation (Tiny vs. Microsoft). Guess I should get it written up as a blog post or three.

Port EmuTOS to it. A nice GPL reimplementation of the Atari ST (68k system) operating system that will fit in a 192kb ROM. These days it's somewhat semi-portable in that it runs on the Amiga and headless on ColdFire eval boards.

That would be awesome! Thanks for the idea.

Please do!

I've started putting something together, but in case I never finish, I've at least tossed the schematics, gerbers, and CPLD source code up on the web, if you're really interested:

  http://coderjames.bitbucket.org

Next I have to figure out how to properly make public the BitBucket repo holding the source code for programs that run on the system.

Very cool!

A 6502 backplane homebrew: http://quinndunki.com/blondihacks/?p=680. Especially impressive because Quinn etched the PCBs at home.

Fast-forward to the finished (and resurrected) project so you can see the backplane: http://quinndunki.com/blondihacks/?p=2644

Amazed and happy to see so much homebrew work still going on. The Veronica project on this site is fascinating.

Let me self-promote my bitbox arm32 home-brewed console since it's somewhat on topic although less retro minded (https://github.com/makapuf/bitbox/wiki) edit : added link

That's a nice project. Ever think about adding an HDMI output? :)

Thanks. Thinking, yes doing ...not yet. I like one-chip designs and generating hdmi data by software can be .. challenging (besides HDMI has many patents).

People should make more 6809 kit computers..

So for example, then you can run OS-9 https://en.wikipedia.org/wiki/OS-9 and emulate an 8080 to run CP/M: https://www.youtube.com/watch?v=FiwmUnLTcjY

I'm just asking, why take that approach vs just building a Z80-based system to run CP/M?

OS-9 is a dramatically more capable OS than CP/M, in that it's a fully multitasking RTOS.

6809/6309 is an awesome processor. But Z80s and 6502s are still being made. And 20mhz range clock speeds. A 6809 or 6309 tops out at under 5mhz and you'll be getting your old chips off ebay, etc.

He was asking why emulate an 8080 on a 6809 to run CP/M on it when you can just use a Z80 and not bother with emulation.

I'm working on something similar. I just got the display working: http://www.exusiae.com/blog/thortron.html

The P112 kit seems better...

http://661.org/p112

It's a nice cp/m kit and can also run a version of UNIX http://p112.sourceforge.net/uzidoc.html

Never mind Alan Cox's Fuzix project.

https://github.com/EtchedPixels/FUZIX

So much nostalgia. I made a 6502 computer from scratch in the middle 90s.

I wire wrapped mine. I did not finish in one evening!

Some additional web references.

I broke mine on assembly. This is how I went about fixing it. https://feilipu.me/2016/06/08/rc2014-troubleshooting/

To reprogram the EEPROM, you need a programmer. This is one I use. https://feilipu.me/2016/06/08/tl866_testing/

I would love if I could set up one of these, a minimalist unix os, and a nice CRT.

For this particular cpu, a good read is [0].

[0] https://github.com/marioaugustorama/uzix-kernel/blob/master/...

It would be an 8-bit processor with no virtual memory. Why not a Raspberry Pi or something more powerful?

I'd love to be able to have the experience of writing all of the code for myself.

Just a C compiler and a text editor and needing to build a world around me.

Would be fun.

It is fun: but I like this kind Bonzai tree thing which is not pactical but a relaxing but challenging experience. And it feel really nice to actually really understand everything for a change.

Any suggestions for something like that? I would love that feel too :-)

I grew up in the 80s with 8 bit computers and started collecting them in the 90s-2000s (when you could pick them up for free as long as you picked them up); I started repairing and extending them picking up video cards and old mobo's from dumps and 2nd hand markets. You can still buy boxes with mobo's from < 2000 which have usable things like memory for much older systems for next to nothing. Using a cheap digi scope, some bread boards, wire and analog electronics can get you quite far in playing around with slow (70-80s) digital components and hooking them up to others. On ebay they sell kits with old processors as I wouldn't recommend soldering apart 80s computers anymore => they are collectible and much appreciated in others or my museum.

That said, it is a good start... If you can find a cheap one, find the schematic online and start checking out the components and measuring the signals. I am lucky to have many systems that have 74series logic + memory + cpu in them which is really easy to follow for any programmer. Most machines from that era won't have that unfortunately.

If you cannot or will not risk that then simply buy a power supply, some packs of analog electronics, digi scope (few $100 one is enough), a box (2nd hand you can get them cheap) of different 74series, breadboard and a computer kit like [0] or [1] or [2] and start experimenting.

[0] http://www.ebay.com/itm/Zilog-Z80-Colecovision-Kit-8MHz-Z80-...

[1] http://www.ebay.com/itm/Zilog-Z80-ZX-Spectrum-Homebrew-IC-Ki...

[2] http://www.ebay.com/itm/Mixed-Kit-6502-or-63C09-or-Z80-CPU-S...

This kit seems very similar to the famous Altair computer which spawned MS-BASIC and CP/M. Anything like Unix and C is not desirable on such a system. Even a 'text editor', as we understand them today, is a reach on such machines.

You could build your own world, but you'd probably have to do it writing ASM out by hand and then entering through a cumbersome line editor. For most purposes, that's too hard, so you would probably invent a very 'basic' line-level interpreter. But, given what we know now, you'd probably come up with a better disk operating system.

It's actually pretty surprising how much you can achieve with these 8 bit processors. My favourite example of pushing the 8 bit Arduino processor to the limit is this - 3D rendering at 320x240 x 16 bit: http://hackaday.com/2016/01/02/better-3d-graphics-on-the-ard...

That demo is rather impressive, but the AVR in an Arduino is much faster than a Z80. This machine is running at ~7.37MHz (which is fast compared to old Z80 based personal computers) whereas the Arduino typically runs at 16Mhz. Further, an instruction takes a minimum of 4 cycles on the Z80 and many take longer whereas most AVR instructions take only a single cycle.

I just went looking at different Z80s and it seems as if there was at least one Z80 made to support a fairly high clock frequency.

The highest I've found that I can order is clocked at 20MHz [0]

[0] - http://www.digikey.com/product-search/en?mpart=Z84C0020VEG&v...

I'm not interested in 3D graphics.

I'm interested in running a keyboard, a terminal of some sort, and some task switching OS.

No sound or anything else needed.

I do remember some of my (much older) friends talking about their Sinclair ZX Spectrum. From what I remember they said they had a Z80 in that.

That old computer was able to do basic text editing from what I remember.

You can do that with a Raspberry Pi.

Funny how things turn around.

I remember still to see this type of kits on sale during the early 80's.

For many it was the only path for their first home micro.

FTA:

> There were no notes on what resistors to fit - so I had to refer back to the schematic on the modules section of the RC2014 site. From here I was able to confirm that they were 2K2 and also note the orientation. it's easy to get the one on the left of the FTDI header in the wrong orientation.

Did resistors become polarised when I wasn't looking?

> Did resistors become polarised when I wasn't looking?

Some of the resistors are mounted vertically. Getting these the right way round is only important so other components physically fit on the board.

I think the FTDI header has resistors that would interfere with an IC socket.

EDIT: And it's nice to use a consistent orientation so it's easier to read the values so it's easier to check your work.

Probably just so they look better in the final build.

Are these real 8 bit CPUs or are they incredibly powerful modern CPUs emulating 8 bit?

Real, the Z80 has been continually produced for decades now.

Which companies make them? I'd be interested to read the specs page for modern Z80 or 6502 CPUs.

It's still Zilog for the Z80 https://www.zilog.com/index.php?option=com_product&task=prod...

Could this be built in Minecraft using redstone?

There's a forum thread on 6502.org discussing the porting of the visual6502 schematics to Minecraft. It would take a lot of effort, and so far not much progress has been made.

http://forum.6502.org/viewtopic.php?f=1&t=3531

Probably. It would take a fair amount of time, though.