4 ms·

I was looking up vacuum tube recently. Apparently there are things called "getter" pins in them that connects to internal material deposition device, used to re

I was looking up vacuum tube recently. Apparently there are things called "getter" pins in them that connects to internal material deposition device, used to remove last bits of air out of tube in the manufacturing line. The exact behaviors and operating parameters for those pins are corporate secrets and not documented. Datasheets only mention them as "No Connect" pins that do nothing and has to be disconnected from anything for safe and correct operation of the device. BACKDOOR!!! in an analog vacuum tube. ... everything ever always had factory-use-only interfaces. Manufacturers don't document every bits of everything on public datasheets. Granted, the dynamics of this change if they can be used as backdoors, and those might have to be either disclosed or securely disabled, but "why they exist in the first place" is just nonsensical question; they exist for necessary internal purposes. That question should be "how should factory use interfaces be handled going forward".

nonrandomstring 2y ago
Great example, and I'm old enough to have also wondered why those "nc" pins on valves and ICs clearly did do something. As you frame it, it's "What the eye doesn't see the heart doesn't grieve". Definitely apropos the making of burgers and sausages. Now we have a different discussion, about "internal" or "external" legibility. We used to live in a world of high trust in vendors. Those days are gone. Vendor malware is a massive and growing problem and supply-chain legibility is a hot topic. FWIW I'm arguing the fully open position. Unless you've desperate trade secrets, there is no "internal". And if you've a 16 bit register that's 65536 entries, most of them sparsely documented as "no op". And if a researcher finds it does something,... it's suspicious by default. This "no user serviceable parts" is an old schism in technology. Today we have almost blanket rights to repair and openness is the new security model.

nonrandomstring 2y ago

Great example, and I'm old enough to have also wondered why those "nc" pins on valves and ICs clearly did do something. As you frame it, it's "What the eye doesn't see the heart doesn't grieve". Definitely apropos the making of burgers and sausages. Now we have a different discussion, about "internal" or "external" legibility. We used to live in a world of high trust in vendors. Those days are gone. Vendor malware is a massive and growing problem and supply-chain legibility is a hot topic. FWIW I'm arguing the fully open position. Unless you've desperate trade secrets, there is no "internal". And if you've a 16 bit register that's 65536 entries, most of them sparsely documented as "no op". And if a researcher finds it does something,... it's suspicious by default. This "no user serviceable parts" is an old schism in technology. Today we have almost blanket rights to repair and openness is the new security model.