Omnimaga

General Discussion => Technology and Development => Other => Topic started by: Keoni29 on March 30, 2013, 05:20:36 pm

Title: Homebrew z80 computer [KEONI-MK1]
Post by: Keoni29 on March 30, 2013, 05:20:36 pm

If you know a better name please tell me :P

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: TIfanx1999 on March 31, 2013, 02:35:51 am

Nice to see that you were able to get it up and running.  :) you should get a cheap low res lcd to hook up to it.

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Keoni29 on March 31, 2013, 02:58:32 am

First I want to make the arduino sequence the programming cycle a bit better. Atm I have to control a lot by hand in order to reset. Once the program is loaded the atmegas will function as a serial interface connected to I/O port1 (port0 is for the LEDs) Then I can use a serial terminal to communicate with the z80 computer

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Keoni29 on April 08, 2013, 07:18:39 am

I got the serial I/O working. The z80 computer can now send characters over serial to a terminal, but it cannot read characters from I/O yet.

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Matrefeytontias on April 08, 2013, 08:30:27 am

Looking great :)

Btw, is there an OS in the z80 computer ? If not, will you write a full one in ASM ?

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Spyro543 on April 08, 2013, 08:59:41 am

What will you use for a terminal; your computer, a "dumb terminal" device, or something else?

If you need any help with stuff I might be able to help, but I know next to nothing about z80s but I can help with general electronics stuff and PICs.

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Keoni29 on April 08, 2013, 11:58:36 am

I want to be able to run CP/M on it or something similar.

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: pimathbrainiac on April 08, 2013, 03:05:16 pm

Noice!

/me wants to build his own

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Keoni29 on April 09, 2013, 02:25:50 pm

Got that z80 in the mail yet? Here are the schematics: http://kaput.homeunix.org/~thrashbarg/Z80SBC.png
I used two atmega chips for I/O operations and booting up from serial.

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Keoni29 on April 18, 2013, 04:26:34 pm

Moving it from the breadboard to a PCB for more reliability and higher cpu speeds. I also reworked the I/O expansion a bit. I replaced the second atmega by two 8 bit latches so I can have up to 16 bits of address space. This is unidirectional, so the atmega will be able to put an address on the address bus, but it cannot read an address which is not a problem since the atmega handles all I/O operations anyways.

Specs for now:
-SRAM 16K (two piggybacked 8k ram chips)
-EEPROM 8K
-Z80 @2MHz
-Shiny led indicators for various cpu flags.
-Atmega for serial communication via usb and programming the eeprom.

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: utz on April 18, 2013, 06:32:58 pm

I'm always impressed by such projects. Been dreaming about building my own computer for some time but I think I'm still a few years away, knowledge-wise. Anyway, congrats and good luck with further developement!

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Keoni29 on April 19, 2013, 03:19:32 am

It took me 2 years to get to this point, but I put a lot of time and efford into my hobby.

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Spyro543 on April 19, 2013, 08:59:22 am

Cool updates Keoni ;) I like the 8K of flash. I'm planning on getting a 1M eeprom for my next computer project :D

Title: Re: Homebrew z80 computer [KEONI-MK1]
Post by: Keoni29 on April 19, 2013, 01:56:11 pm

The new eeprom arrived! Let's hope this one does work :P