Sorry for this naive question, but isn't every network card build out of discrete logic components?
Show HN: I made a discrete logic network card
31–40 of 91 posts
Re: Show HN: I made a discrete logic network card
#32Very cool stuff! Only nitpick I'd have is that author decided to use a custom-design cpu. Ok, "discrete logic only!" is a valid choice. And then keeping complexity to a minimum weighs heavily. But the downsides of that choice are also considerable: -No interrupts (which are very useful) -No existing software base to tap from. Somewhat-useful C compiler helps.. somewhat. But who am I to question author's choices for a…
What does "discrete logic" mean in this case? Why would this prevent interrupts?
> What does "discrete logic" mean in this case?
74xx series ICs (eg. 74ACT family in case of the cpu, if I read correctly).
More generally, it may refer to "basic logic elements whose function is easily inspected".
> Why would this prevent interrupts?
Not at all - in theory.
In practice, interrupt support tends to complicate cpu designs. Complicate = more logic = more ICs. So builder decided against it & chose not to implement interrupts on the cpu.
Re: Show HN: I made a discrete logic network card
#33Sorry for this naive question, but isn't every network card build out of discrete logic components?
Discrete is the opposite of integrated, as in integrated circuit.
In practice, it means using multiple components. In a strict sense it means no integrated circuits at all, I suppose. But it's also a relative thing. So while a 7400 series chip is not a "discrete" component as most would think of it, using a hundred 7400 series chips to implement a processor is relatively more discrete than a microprocessor. (It's certainly not as integrated.)
Since the early 1980s, Ethernet interfaces have used used custom chips, because the amount of logic required would need dozens of gate-level chips otherwise (as seen here!)
Re: Show HN: I made a discrete logic network card
#34Sorry for this naive question, but isn't every network card build out of discrete logic components?
No, network cards use chipsets, meaning, most of the logic is inside one or two large ICs (Integrated Circuits). What the poster is doing is creating a card using the simplest existing ICs which contain simple logic circuits such as NANDs, multiplexers, etc.
Re: Show HN: I made a discrete logic network card
#35Sorry for this naive question, but isn't every network card build out of discrete logic components?
No, most use much more complicated ICs. This isn't fully discrete (individual transistors, diodes, etc.) but only uses 7400-series logic ICs, not ASICs.
Re: Show HN: I made a discrete logic network card
#36Super impresssive! I would absolutely love to work on such projects and admire the passion and countless hours that went into understanding and then building the system. Retirement is not something desirable for me, so maybe that's when I'll spend my time on hardware and software projects like this.
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Re: Show HN: I made a discrete logic network card
#37A network card with opaque firmware is a 0-day away from becoming a global catastrophe. Even RISC-V based switches like the Vega use proprietary switch chips (Wuhan China designed FSL91030M specifically), which is no better. You can verify input/output to a certain extent, but this doesn’t preclude a timer based function call or a tailored packet activation. I wonder why our society tolerates these unknowns. With the…
> these unknowns
Sorry to throw a Rumsfeld at you, but I think these are "unknown unknowns".
If people were aware of the presence and significance of such critical knowledge voids I do not believe they would tolerate them.
I see it as the job of civic cybersecurity to bring precisely these sorts of things to wider attention and educate folk on why they are are problematic.
Re: Show HN: I made a discrete logic network card
#38Sorry for this naive question, but isn't every network card build out of discrete logic components?
Discrete is the opposite of integrated, as in integrated circuit. In practice, it means using multiple components. In a strict sense it means no integrated circuits at all, I suppose. But it's also a relative thing. So while a 7400 series chip is not a "discrete" component as most would think of it, using a hundred 7400 series chips to implement a processor is relatively more discrete than a microprocessor. (It's cer…
ah, that makes sense. Thanks!
Re: Show HN: I made a discrete logic network card
#39> Fixing the frame length doesn’t have any effect on higher-level protocols because they encode the packet size in their headers and do not rely on the actual Ethernet frame length. Interesting. I just wrote a packet decoder and I specifically verify at each layer that the lower layer length matches. So for IP, in my decoder the IP datagram length must match exactly the ethernet frame length + link layer header. I di…
Timestamps and other types of in-band network telemetry are sometimes inserted in the frame as a trailer (with a new FCS). If an application isn't looking for the L2 data, it's just ignored by the Linux IP stack.
Re: Show HN: I made a discrete logic network card
#40A network card with opaque firmware is a 0-day away from becoming a global catastrophe. Even RISC-V based switches like the Vega use proprietary switch chips (Wuhan China designed FSL91030M specifically), which is no better. You can verify input/output to a certain extent, but this doesn’t preclude a timer based function call or a tailored packet activation. I wonder why our society tolerates these unknowns. With the…
> these unknowns Sorry to throw a Rumsfeld at you, but I think these are "unknown unknowns". If people were aware of the presence and significance of such critical knowledge voids I do not believe they would tolerate them. I see it as the job of civic cybersecurity to bring precisely these sorts of things to wider attention and educate folk on why they are are problematic.
I think visibility is one aspect, but not the whole story. An average home user runs Windows and doesn’t necessarily care if a hypothetical backdoor could exist in their hardware/software stack.
They browse the web, do their banking, and share photos on SM after checking their mail and searching for Tiramisu recipes.
The existential threat to themselves is low, so they don’t dig further into the ramifications. Journalists, whistleblowers, activists, “undesirables”, those are the primary concerned parties.
The civic cybersecurity aspect needs to lay out a clear benefit to free speech and oppression which makes tangible sense to day to day life. I’m not quite sure how to spread this level of awareness, or highlight the importance of such measures in a way that hits home.