Is the copyrights on the Z80 still valid ?!?!?

Door WORP3

Paladin (828)

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06-10-2011, 21:56

Does anyone know if it is legal to make a Z80 binary compatible CPU and sell it ?

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Van Sd-Snatcher

Hero (582)

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06-10-2011, 22:22

Ask zilog.

Van slowerisbetter

Master (194)

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06-10-2011, 22:24

Correct me if i'm wrong, but you can create a compatible CPU, you just cannot copy the exact design of Zilog.

Van WORP3

Paladin (828)

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06-10-2011, 22:38

You are correct i can't copy the exact design and actually i don't want to as it will keep me in stuck in the retro time. But the last thing i want is that after investing a lot of time that Zilog is going to nag Wink
There are a lot of Z80 cpu's made by other company's but you never know if they are paying Zilog or not ?

Are there any known problems (copyright based) with the T80 core used within the OCM ?

Van bore

Master (135)

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06-10-2011, 23:00

Chip design is not protected by copyright but is convered under different laws.
Check the wikipedia page for Integrated circuit layout design protection

Since the Z80 was designed 1976 and the Semiconductor Chip Protection Act wasn't written until 1984 the mask was never specifically protected and it might have been allowed to copy the cpu directly without modification. (But not tested in court as far as I know.)
Even if the SCPA would apply to the Z80 the protection would still have expired by 1986.

I am not sure what the rules are for protecting an instruction set. AMD is making binary compatible versions of the x86 CPU, the history of AMD vs. Intel is not free from legal battle but as far as I can tell nothing of it is about using the instruction set specifically.

Van bore

Master (135)

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06-10-2011, 23:11

This section from the wikipedia page might be of interest to you. (And as usual wikipedia is not an authorative source so it might have to check the actual source.)
Note that the exclusive rights granted to mask work owners are more limited than those granted to copyright or patent holders. For instance, modification (derivative works) is not an exclusive right of mask work owners. Similarly, the exclusive right of a patentee to "use" an invention would not prohibit an independently created mask work of identical geometry. Furthermore, reproduction for reverse engineering of a mask work is specifically permitted by the law. As with copyright, mask work rights exist when they are created, regardless of registration, unlike patents, which only confer rights after application, examination and issuance.

Van RetroTechie

Paragon (1563)

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06-10-2011, 23:31

There are a lot of Z80 cpu's made by other company's but you never know if they are paying Zilog or not ?
AFAIK most non-Zilog Z80s were made under license (except eastern European clones), that is: Zilog provided design to others (starting with Mostek). Perhaps for royalties or other deals, perhaps for free. Why? Having multiple suppliers is sometimes just what makes an end-product manufacturer decide to go with a certain part. Less worries about future availability & such. So this would still be in Zilog's interest, simply to make the Z80 more popular.

Copying the function of a circuit isn't a copyright issue since you're not copying the original ! Surely there's a number of commercial applications for clones like the T(V)80, and Zilog would be laughed out of court if they'd send lawyers after that.

Are there any known problems (copyright based) with the T80 core used within the OCM ?
Yep, you have to honor the copyrights that T80 core comes with... :D

Van WORP3

Paladin (828)

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07-10-2011, 08:47

Thanks for the information !

Mmm, so it's like always, do what you like and deal with it when they are going to nag about it.
But you all are right, if it's going to be a problem it's because of some patent, not copyrights !

When searching for z80 patent stuff, you will find a lot z80 related patents of zilog but are they still valid ?
Is the patent expiration date still +20 years ?

Van X68000

Rookie (25)

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22-10-2011, 08:40

Are you going to make it pin-compatible?

Van WORP3

Paladin (828)

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22-10-2011, 08:54

Are you going to make it pin-compatible?

Not really. It isn't even possible as i can't fit all the signals on the old package.