Good 8-bit kit for beginner?

[Hugo Holden]

Hi All,
I was wanting to build a kit for either a 6800, 6502, or 8080 CPU and wondering if anyone had any recommendations for a beginner? Beginner in terms of electrical engineering experience, definitely comfortable with programming just not verse in the ways of doing my own electronics. Was hoping I could start with a simple kit and go from there?

Thanks,
Chris

On the other hand if you are already good at programming and its electronic construction etc, you could really start with any kind of electronics project, it wouldn't even have to be a computer, it could be practically anything in the field, some computer test gear, audio & video amplifier kits etc build up your soldering , de-soldering and electrical and mechanical construction skills, the World is your oyster. A good project would be something that could help fix computers too, like a logic probe.

 

[chreeg11]

Hey all, sorry didn't realize there were more responses (wasn't getting notifications)! I got the RC2014 for xmas from wife and finally just tried power up. Worked on first try!

G Searle 32k Z80SBC

<C>old, <W>arm or <M>onitor? C

Memory top?
Z80 BASIC Ver 4.7b
Copyright (C) 1978 by Microsoft
32382 Bytes free
Ok
10 for a=1 to 5
20 print "rc2014 is cool"
30 next a
run
rc2014 is cool
rc2014 is cool
rc2014 is cool
rc2014 is cool
rc2014 is cool
Ok

 

[Brown]

6502 used in Apple II series, and to have many programs.

 

[Plasmo]

RC2014 is a good choice, but it is rather expensive. Thinking about how to test cheap retro components, I've designed this barebone Z80/6502 board that can run Z80, 6502, and an unspecified 40-pin processor. The bus connector is RC2014 bus when populated with Z80. This barebone Z80/6502 computer only has 3 IC so should be cheap to build. Nevertheless, it is quite fast--25.175MHz because I want to experiment with VGA beam racing.
Bill
PS, all the components (except W65C02) are used components from eBay. eBay's Z80 will run 25MHz generally,, but 6502 from eBay will never run at 25MHz; most of them are only good to 2-4MHz.

 

[whartung]

but 6502 from eBay will never run at 25MHz; most of them are only good to 2-4MHz.

The WDC 6502 will go 14MHz out of the box, you may well be able to push it further.

 

[Plasmo]

WDC6502 did a die shrink a while ago and is now 0.6u TSMC. Its spec remained at 14MHz, but experimentally it is good to about 36MHz and passing Klaus Dormann instruction tests. 25MHz is easily achieved which is really quite fast, it's like a 50-60MHz Z80.

 

[Eudimorphodon]

RC2014 is a good choice, but it is rather expensive. Thinking about how to test cheap retro components, I've designed this barebone Z80/6502 board that can run Z80, 6502, and an unspecified 40-pin processor.

Curious with this thing about how you’re loading code into RAM without any ROM to hold bootstrap code? Also, is the serial port bitbanged using a port decoded by the GAL?

 

[Plasmo]

The GAL is 22V10 which has 10 outputs. 8 of the outputs are ROM data output. Depending on the data patterns, 22V10 can hold 40-50 bytes of instructions, maybe more. The ROM is a bit-bang serial bootstrap loader at 115200N82. Z80 needs 36 bytes of instruction, but 6502 needs 47 bytes because top of memory is 6 bytes of vectors. It is the fast ROM in 22V10 that allows processors to run 25MHz, no wait state. The other 2 outputs are bit-bang serial transmit and RAM enable. For Z80, the serial port is mapped to I/O space so the entire 64K memory is available. It can run CP/M, in fact.

Program needs to be serially loaded every reset, but at 115200 bps and with TeraTerm macro script it can load under 5 seconds.

 

[Eudimorphodon]

Depending on the data patterns, 22V10 can hold 40-50 bytes of instructions, maybe more.

... huh. I guess I can see how that would work, but I can imagine it was loads of fun encoding it. (Given the output pins are limited to between 8 and 16 ORs, depending on the pin, a straight-up "each address is an equation" encoding would seemingly limit you to around 10-12 bytes.) You don't happen to have a github or whatever with your source on it, do you?

 

[Plasmo]

It is actually quite a bit easier than you might think. WinCUPL has a TABLE keyword for lookup table and ROM that generates the logic equations automatically. I imagine it is just eight Karnaugh map generators with 6 addresses as inputs and data bit as truth table; one Karnaugh map per data bit. All I do is cut and paste the hex outputs into WinCUPL's TABLE statement and press "compile".

I have a homepage for prototype version of barebone Z80 here. 22V10 design file is there along with some software. I need to put together a homepage for combined Z80 and 6502.

Edit, oh wait, I also have barebone 6502 here. I previously called it "Muntz65", named after "madman" Muntz for brutal simplification.

 

[famicomaster2]

I like Ben Eater's kit. Video assembly instructions, pretty good price for the kit, goes on sale pretty often, includes everything you need in the box except an EPROM programmer. He even goes so far as to explain pretty in depth how to write software for it as well, if you like.