A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

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Just4Fun
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A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby Just4Fun » Sat Dec 17, 2016 5:28 pm

Hi all,
I've just finished my last crazy useless project :lol: (those I like more...):



More info here:

https://hackaday.io/project/19000-a-4-4ics-z80-homemade-computer-on-breadboard

Cheers.

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ahull
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Re: A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby ahull » Sat Dec 17, 2016 8:41 pm

The needed ICs are:

Z80 CPU CMOS (Z84C00) 4Mhz or greater ($1.16)
Atmega32A ($1.70)
TC551001-70 (128kB RAM) ($1.10)
Z80 CPU CMOS (Z84C00) 4Mhz or greater ($1.16)


? Two Z80 CPUs and no ROM ?
- Andy Hull -

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RogerClark
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Re: A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby RogerClark » Sat Dec 17, 2016 8:59 pm

Thats twice as much RAM as address space. But I presume thats the smallest RAM you can buy, or perhaps the cheapest.

I quite like the Z80. I prefer it to the 6502.

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Re: A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby Just4Fun » Sat Dec 17, 2016 9:03 pm

Only one CPU (Z80) and no ROM!

The MCU Atmega32A "emulates" ROM, I/O for User led and User key, UART with interrupt, clock generator (@4MHz) and reset generator....

Only 4 ICs... :D

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Just4Fun
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Re: A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby Just4Fun » Sat Dec 17, 2016 9:09 pm

RogerClark wrote:Thats twice as much RAM as address space. But I presume thats the smallest RAM you can buy, or perhaps the cheapest.

I quite like the Z80. I prefer it to the 6502.



Yes, it the cheapest SRAM... but I have find the way to use it all... may be a new HW revision if I have the time...

The Z80 is cheapest than the 6502... (try to do a search on ebay...) and is CMOS too...

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Re: A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby Just4Fun » Sat Dec 17, 2016 9:18 pm

ahull wrote:The needed ICs are:

Z80 CPU CMOS (Z84C00) 4Mhz or greater ($1.16)
Atmega32A ($1.70)
TC551001-70 (128kB RAM) ($1.10)
Z80 CPU CMOS (Z84C00) 4Mhz or greater ($1.16)


? Two Z80 CPUs and no ROM ?


Ops.. was a typo.. just edited..

Thanks ahull!

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ahull
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Re: A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby ahull » Sat Dec 17, 2016 10:30 pm

Yes the 65c02 is a whopping $2.82... but it's a rocket ship at 10MHz :P Knocks spots off the 4MHz Z80
http://www.ebay.com/itm/1pcs-W65C02S8P- ... 1988044104
.. but you can go slower.. for less.. ($1.60)
http://www.ebay.com/itm/1PCS-Microproce ... SwZVlXvWq~
- Andy Hull -

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Just4Fun
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Re: A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby Just4Fun » Sat Dec 17, 2016 10:42 pm

ahull wrote:Yes the 65c02 is a whopping $2.82... but it's a rocket ship at 10MHz :P Knocks spots off the 4MHz Z80
http://www.ebay.com/itm/1pcs-W65C02S8P- ... 1988044104
.. but you can go slower.. for less.. ($1.60)
http://www.ebay.com/itm/1PCS-Microproce ... SwZVlXvWq~


Interesting..

Anyway the Z80 i bought for $1.16 is this one:

http://www.ebay.com/itm/1PCS-Z80-CPU-Microprocessor-IC-ZILOG-DIP-40-Z84C0020PEC-Z80CPU-Z80-CPU-/361561098024?hash=item542eb88728:g:SxgAAOSwf-VWYwdX

and is 20MHz! :D

The 4MHz is due to the clock generation with the Atmega32A (just to stay into the 4$ range...)

I could have used an EXO-3 at 16MHz as clock generator for both (Z80 and Atmega32A), but this would increase the cost...

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Re: A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby RogerClark » Sun Dec 18, 2016 2:36 am

andy

It was years ago I used a Z80.

I recall the Sinclair computers (Z80) vs the BBC (6502), but I don't recall the BBC being any faster - but perhaps it was.

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Re: A 4$, 4ICs, Z80 homemade computer on breadboard: Z80-MBC (Mobile Breadbord Computer)

Postby Pito » Sun Dec 18, 2016 9:45 am

Z80 needs more clocks per instruction than the 6502 afaik (at least with 8bit instrs).. I've spent most of 80ties with Z80 too :) (and with 68k).
Got an 68B09 recently, but not used yet.
Great usage of mega32 as an ROM and IO! I wonder why not use it at 20MHz and Z80 at 10MHz. A worth of a 20MHz canned oscillator (or a crystal) to add.


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