Legal Issues Reproducing Old CPU

Almost certainly, TI will be unhelpful here. To give a proper answer, they would have to involve their own lawyers to figure out what to say, and that is simply too expensive for a case like this. So they will either say nothing at all, or say "No". If you are really lucky, you might get something that implies that they don't care, without actually saying so directly.

I think, however, that /if/ things get ugly in the future and TI tries to sue you, then you could point to such an conversation with TI as evidence that you did your best to do the right thing.

Reply to
David Brown
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(snip)

Note that not all companies are like that. Sun released verilog code for 64 bit SPARC. You can legally build and sell one. It seems to be now on the Oracle web site.

-- glen

Reply to
glen herrmannsfeldt

I don't mean to say that TI are particularly secretive or awkward about these things. It's just a matter of economics - a big company is unlikely to give you permission to copy their IP without first passing it through the lawyers. When it is an active decision from the company

- such as with Sun, where they felt it would be a good idea if more people used SPARCs even if they were not made by Sun - it is worth calling the lawyers. When it is a single person asking, with no return for TI, then doing things legally correctly means quite a lot of time and money for TI. While TI staff have always been nice and helpful in my experience, there is a limit to how much you can expect them to do to be "nice".

Reply to
David Brown

I agree with Tim on using an emulator if you can. I do not see why you need to get down to the gate level. I have never done any work with this CPU but a quick search brings up many emulators for the TI-99 game system that, from what I read, used the TMS9900. Pull the core cpu emulator code out of one of these and put it in a fast micro, possibly one that will run out of SRAM. You can tie the micro's ISR into the emulator so you get good interrupt timing. You will still probably have to hang some interface logic around the micro.

The nice thing about using the emulator is you can get it running on a PC or even a target micro development board, and get the basic bugs worked out.

The HDL approach would be a very interesting project and a lot of fun but I think you are under estimating the level of effort to take something from OpenCores and get it to production level.

--
Chisolm 
Republic of Texas
Reply to
Joe Chisolm

TI recently released a lot of code for a slightly newer CPU, I think it would be worth talking to them about the 9900.

Reply to
Robert Swindells

Am Freitag, 27. September 2013 15:32:31 UTC+2 schrieb David Brown: [...]

In the case of the MSP430 microcontroller series, TI links to Opencore's openmsp430 implementation from their Open Source Projects wiki page (which at least seems to be a semi-official resource):

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While the openmsp430 is, of course, an open source project, it has been successfully used in various commercial projects IIRC (it's also been implemented in an ASIC, so that doesn't sound quite like a hobby project anymore).

-- Michael

Reply to
Michael Engel

I - not being a lawyer as well - think that this simple CPU would not cause legal problems. CPUs that use microcode probably would - if you don't create the microcode part on your own but copy it from, say, a BIOS which dynamically updates the genuine chip.

Even conservative copyright fighters should agree that it is kind of strange to copyright simple commands like branch if not zero, add a

Reply to
Stefan Huebner

I don't think you can copyright an instruction set, can you? I thought that some of the "classic" reverse engineering precedents had addressed that. Similar to the old "clean room BIOS reverse engineering" exercises.

I am not a lawyer, and no one should take this as proper legal advice, but I believe if you design the processor logic in an "untainted" way (i.e., you don't literally steal circuitry or microcode) then you are free to design a gadget that uses any instruction set you wish.

-- Kip

Reply to
Kip Ingram

Copyright applies to the expression of an artistic work. So no, an instruction set can not be copyrighted. However, the nemonics for opcodes can. That is why Zilog had to use a different assembler for the Z80 even though it was binary upward compatible with the 8080.

--

Rick
Reply to
rickman

Yeah, that makes sense... So you can functionally duplicate a processor, but not "artistically." Good distinction...

-- Kip

Reply to
Kip Ingram

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