Z80 SIO 0/1/2 NMOS & clones on RC2014

[Martin Niec]

Hi Guys,

I would like to try and hopefully have fun with different SIO chips, have you tried SIO clones and what success did you have with NMOS versions? eBay is full of them and CMOS versions are more pricey...

[David Reese]

On 8/4/21 6:14 PM, Martin Niec wrote:

Hi Guys,

I would like to try and hopefully have fun with different SIO chips, have you tried SIO clones and what success did you have with NMOS versions? eBay is full of them and CMOS versions are more pricey...

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Well, just on the face of it, you should expect a higher power consumption, higher noise figure, and lower speeds with NMOS as compared to CMOS.  There's a reason for the price difference.  You may find that the cost of implementing NMOS SIO interfaces is offset by higher discrete component count.  It will pay you well to do the research on this before laying out your hard earned cash, especially if you intend to bring something to market.

I'm not saying it can't be done, but perhaps it shouldn't be done.  A lot will depend on the particular Z80 variant you will be using - there are both CMOS and NMOS versions of the Z80 out there.  You should match your existing technology.

Datasheets for CMOS and NMOS Zilog Z80/Z84C00 CPUs here:  https://www.zilog.com/docs/z80/ps0178.pdf

Respectfully,
David