Why did Sinclair hate National Semiconductor?

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Why did Sinclair hate National Semiconductor?

Postby Dave » Thu Jan 11, 2018 7:23 am

Screen Shot 2018-01-11 at 1.20.39 AM.png

From the QL Service Manual, it seems Sinclair Research had no love for National Semiconductor.

Is there a backstory to this?

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Re: Why did Sinclair hate National Semiconductor?

Postby XorA » Thu Jan 11, 2018 10:53 pm

Ah crap I have seen this somewhere before (not for QL) but I can't remember where!

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Re: Why did Sinclair hate National Semiconductor?

Postby Pr0f » Fri Jan 12, 2018 7:22 am

I wonder if it was a loading issue, or maybe slew rate ?

Without comparing the data sheets for NAT semi and maybe TI or whoever else also made the LS series of logic, it's hard to say.

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Re: Why did Sinclair hate National Semiconductor?

Postby Zarchos » Fri Jan 12, 2018 10:26 am

You'll have to check the various interviews on YT, but I remember Steve Furber or Hermann Hauser (Acorn) explaining
that the Beeb did (or did not) work (only, or no at all) with some NS chips.
And they never understood why. (For the exact same specs compared to equivalent parts from other founders).

Owner of various QLs including accelerated beasts, and also a happy Q68 owner ;)
Now porting SOTB to the Archies, to then port it to the Q68.
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Re: Why did Sinclair hate National Semiconductor?

Postby 1024MAK » Sun Jan 14, 2018 6:04 am

They DID NOT hate National Semiconductor.

Every manufacturer of so called standard 74 series logic uses their own internal logic design to fulfill the overall logic function. This means that logically, a 74 series part from any manufacturer should work. However, timing wise, they may not work the same. And any undocumented features or functions may also not be the same (for example, undefined logic states).

Sinclair found that some 74 chips from National Semiconductor did not work the way they wanted them to. Hence the warnings in both the ZX Spectrum and QL service manuals.

But other manufacturers also some chips that were not recommended in some applications.


QL, Falcon, Atari 520STFM, Atari 1040STE, more PC's than I care to count and an assortment of 8 bit micros (Sinclair and Acorn)(nearly forgot the Psion's)
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Re: Why did Sinclair hate National Semiconductor?

Postby Silvester » Thu Jan 18, 2018 12:16 pm

My old Elektor data book remarks the Hitachi 245 has Schmitt inputs, which make them suitable for noisy signals.

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