[HN Gopher] Strange chip: Teardown of a vintage IBM token ring c... ___________________________________________________________________ Strange chip: Teardown of a vintage IBM token ring controller Author : parsecs Score : 86 points Date : 2021-02-28 18:06 UTC (4 hours ago) (HTM) web link (www.righto.com) (TXT) w3m dump (www.righto.com) | devoutsalsa wrote: | I worked on a token ring network back in the 90s. There were more | employees than network ports. So every time someone complained of | not having network connectivity, we'd find a network cable where | the light on the port wasn't lit up from activity, usually | because someone was out sick or on vacation. If everyone decided | to come into the office, we would have had a problem, but I don't | think it ever happened while I was there. | nullc wrote: | The cards are supposted to bypass themselves when powered off, | that's what those relays were for. | | Later they had these MAU devices that let you build star like | topologies where the mau would bypass inactive ports. | devoutsalsa wrote: | Yeah, we had an MAU, but I'd forgotten the term. | 2sk21 wrote: | I encountered the wierd token ring connector for the first time | when I joined IBM in the early 1990s. But the proprietary | connector got replaced with a standard RJ45 jack later on. But by | that time, it was clear that Ethernet had won. | TedDoesntTalk wrote: | Token-ring networks could have ruled the world. But IBM's | insistence on licensing fees made the equipment expensive | compared to Ethernet. | | Token-ring was faster: 16 Mbps with no collisions, vs Ethernet's | 10 Mbps in a perfect world... but in reality it was slower when | accounting for collisons and retries. No so with token ring. | | If IBM had licensed the tech without fees, hardware would have | been competitive to Ethernet and today we'd all be using 1 Gbps | token ring in our homes. | | But now I'd be surprised if a token-ring driver even exists for | Windows 10 or MacOS. | gumby wrote: | The biggest problem with token passing systems is the cost of | losing the token (machine holding it crashes) or failing to | yield (when you then have a pope-antipope situation). | | Ethernet has an immediately worse system (everybody has to do | the backoff, and on a crowded network that can be painful) but | on an amortized bases not-as-bad system. Also adding more hosts | is pretty much automatic. Consider it a positive example of the | "worse is better" paradigm. | rodgerd wrote: | Licensing (alongside the MCA debacle) was definitely a driver, | as was the more complex topology for even a simple token ring | network compared to a simple ethernet network. | | Ultimately the brute-force improvement in efficiency given by | developing ethernet switching settled the argument, IMO. Once | you could practically utilize the bulk of the theoretical | bandwidth of ethernet, token ring was toast. Switching was the | Pentium Pro of network architectures. | LargoLasskhyfv wrote: | Ahem! https://en.wikipedia.org/wiki/ARCNET | jhoechtl wrote: | Connectors have been bulky and wires thick compared to | ethernet. | wmf wrote: | Which was just IBM over-engineering. Token ring ran fine on | cat5 with RJ45. | pontifk8r wrote: | When tearing down some of this technology, there's almost an | undercurrent "how this works is a mystery today" -- but the | humans that still worked on some of these micro-marvels are | probably still alive. Have you had success in finding people that | did work on these designs, for example in the case of the | "universal controller (UC) architecture" which might merit an | article all its own? | kens wrote: | I've asked around a bit, but haven't found anyone with | information on the UC architecture. | reaperducer wrote: | I wonder if it's buried somewhere in Usenet. | a-dub wrote: | i didn't know the actual data got passed from host to host... i | was always under the impression that the data was broadcast and | merely the token or "talking stick" got passed from host to host | in a ring. | kens wrote: | Author here if anyone wants to discuss IBM's chips. | h2odragon wrote: | Could the mystery analog loops be impedance matching / baluns? | My first thought, the way they stand out bare on the chip, | seems similar to other RF magic. | kens wrote: | The mystery loops might be some sort of impedance matching. | 16 megahertz seems low for that sort of magic, but I don't | know. | ch_123 wrote: | > IBM calls this "microcode", but it's unclear if this is | microcode in the usual sense or just firmware instructions. | | IBM had all sorts of unconventional usages of the word | "microcode", e.g. parts of the OS/400 operating system were | referred to as the "Horizontal and vertical microcode" (they | were in fact the kernel of the operating system) | realo wrote: | This flip chip was likely made at the IBM Bromont plant in | Quebec. | | I visited it a long time ago. | | If you x-ray (?) or break the ceramic substrate (with the | actual pins) you might find it to be a complex multi-layer | piece ... | 7800 wrote: | What is the strangest thing you've ever seen in a chip? (e.g. | has anything ever hinted at either a lucky accident that relied | on physical laws that weren't understood or tech that seemed | too advanced to have been developed by the team that developed | it?) | | Also- the strange parts of the chip spell DDB, which may be | relevant, as the V DDB is mentioned in one of the MAU design | patents. Or DDB possibly could be the initials of the team or | designers. It could have also served a practical purpose. | kens wrote: | I've seen a few things on chips that don't make sense, such | as wires to nowhere. Then I figured out that these were bug | fixes where they had cut connections. | | Occasionally I find interesting chip art such as a tiger on a | Dallas Semiconductor chip: | https://en.wikipedia.org/wiki/Chip_art | kayson wrote: | Chip art is a lot of fun! Years ago when I was working at a | startup, we had a wooden statue in the office of a monkey | holding a cell phone. Over time he was further accessorized | with a hardhat and an official company badge. On one of our | prototype tapeouts, we made a not-insignificant effort to | render a proper photo of it onto the top layer metal. | | The tricky thing was getting multiple colors (shades, | really) using what amounts to a single color. Back then, we | didn't have any fancy filters like "sketch mode" to turn it | into a line drawing, and we were limited to some extent by | process design rules for metal size, spacing, density, etc. | | We ended up opening the image in GIMP, and converting it to | grayscale, then true black and white (1-bit color) by | upscaling and using some filter where it preserves the | shades by setting the average density of black pixels in an | area to match the shade of gray of the pixel in the | original. Then we wrote a script that mapped black pixels | to solid metal, and white pixels to empty space, on a grid | in such a way that all Design Rules were met. | | It wasn't a perfect result but I think it turned out | alright! https://imgur.com/a/AkB10A0 | parsecs wrote: | What was the function of that piece of silicon? | kayson wrote: | The whole die was a cellular transceiver. If I remember | correctly that particular spot happened to be empty on | the top layer. Foundries require a minimum density of | metal on every layer, so we would have had to put dummy | pieces of metal there anyways. We figured why not put a | picture | bogomipz wrote: | This was another great post. I hope to see you do an Ethernet | chip/card post in the future. I had a couple question about the | following: | | >"The block diagram below shows the complex functionality of | the chip. Starting in the upper right, the analog front end | circuitry communicates with the ring. The analog front end | extracts the clock and data from the network signals." | | Do all non-optical network cards have a similar analog circuit | as well? Is this generally the transceiver chip on the card? | | >"The chip's logic is implemented with a CMOS standard cell | library and consists of about 24,000 gates. The idea of | standard-cell logic is that each function (such as a NAND gate | or latch) has a standard layout." | | Are these cell libraries the same as an IP block that you would | license today when designing a chip? Did cell libraries become | common around the time of this chip? | kens wrote: | I haven't looked at Ethernet chips in detail, but they have | similar analog circuitry. A "PHY" (physical layer) module | does the analog encoding and decoding. | | Standard cell libraries are lower-level than IP blocks since | you're dealing with gates rather than functional units. I'm | sure someone here knows about how they are licensed. | | On the chip I looked at, the analog module and the CPU were | treated as IP blocks. These blocks were built by IBM so the | intellectual property itself wasn't an issue. But the blocks | were designed by other teams and essentially dropped onto the | chip unchanged. For the revised version of the chip, they | redesigned the logic but kept the original analog and CPU | blocks. | dfox wrote: | > Do all non-optical network cards have a similar analog | circuit as well? Is this generally the transceiver chip on | the card? | | Even optical cards have this kind of circuitry in the PHY | chip. While the SFP module usually contains surprising amount | of logic, most of it has to do with configuration and testing | and in the end it is just an pair of LEDs with configurable | analog amplifiers. | | On the other hand for modern ethernet over TP (1Gbps and up) | the analog interface circuitry is significantly more complex | (and power hungry), because calling the thing baseband (the | "base" in "1000-base-T") somewhat stretches the definition of | the word. It uses various line coding and signal processing | tricks to squeeze all the bandwith out of the wire. ___________________________________________________________________ (page generated 2021-02-28 23:00 UTC)