A 4$, 4ICs, Z80 homemade computer on breadboard

[Just4Fun]

Hi all,
this is my first post here.

I've seen here some members interested in retro computing, and here it is my own "interpretation" of this theme.

And with the cost of only 4$ (buying components from ebay...) it is possible to taste some flavor of retro computing...

Here a short video: https://youtu.be/7eSbZ2Hu_6s

Here all the details of the whole thing: https://hackaday.io/project/19000-a-4-4ics-z80-homemade-computer-on-breadboard

PS: I'm not interested about selling anything.. I've done this only for fun!

Cheers

[Roeland_R]

looks great.

[Just4Fun]

Thanks! 

[Ian.M]

Interesting.  Do you reckon the I/O could be crammed into an Arduino Nano to get it all on the breadboard?

However its NOT a good idea to put music on your Youtube videos if you want them to stay up.  Its only a matter of time before a DCMA takedown is requested by one of the companies that trolls media copyrights.  Exception: if you have releases in writing from both the original composer and the performer so can contest the takedown.

[Just4Fun]

Hi,
Arduino Nano (aka Atmega168/328) doesn't have enough I/O pin. May be adding one or two 74HC373 or 374 or something like that. But you need to modify the sketch.

About the music, I used only "free" soundtracks provided by youtube itself (using the youtube video editor), so it should be DCMA free... 

[westfw]

That's very nice!  The same ATmega32 chip/flipflop could probably be adapted to work with a lot of other chips from that era as well.
I've been thinking of doing something like this for a while, but I was looking at 8051, which doesn't have the "wait" input, and so I didn't think of using a flipflop...

How does it "boot"? 

[T3sl4co1l]

Z80 sure is nice, isn't it?

I made this years ago,
https://hackaday.io/project/18898-z80-breadboard-display
same idea, different ports/peripherals.

Tim

[Just4Fun]

How does it "boot"?

Hi,
It uses a 2 phases boot process.

At first the Atmega32A uses a DMA access to SRAM to copy a small loader.
Then it releases the bus and the Z80 starts to execute the loader that relocates itself at the bottom of the memory address space and loads from the Atmega32A (this time used as a sequential ROM in the I/O address space) the final ROM image.

After this second load phase it jumps to the image starting address and execute it.

[timothyaag]

Very neat. The smartphone controller isn't something I've seen before in a Z80 computer. I might take some inspiration from you when I move my Z80 computer from being 90% controlled with an Arduino to a standalone design. 

[slicendice]

Very interesting project. A starting point for developing a TI-85 (Texas Instruments Graphing Calculator) clone on a breadboard. Love it!

[Dan Moos]

It's there a web community focused on this sort of thing? I'm not sure if it's something I'd do or not, but just eavesdropping on such a thing would be fun if nothing else.