Ethernet also got *way* more market traction, because it was infinitely more survivable.
One of my early jobs was managing a Token Ring network, and we spent our days running around a 13 floor building, chasing machines where people had kicked connectors out of walls, just enough to stop data, but not enough to make the MAU do the self isolation. We had a piece of software called the Cabletron TR Manager - that monitored the ring for beaconing, and let us know the upstream node that detected the break. Then we would consult our *detailed* notes on what cards were installed where, so we could find the culprit that was broken. Without the notes, we would have had zero chance. Heady days. I suggested to the network manager at the time that we could transition from TR to Ethernet (everything was wired with Cat3 Shielded cable - but he didn't want to, because "Ethernet had collisions" - that was when I discovered that everybody has limitations that something breaks their thinking. After a while I convinced him to transition one of the Cabletron cards to Ethernet, and do a test on a 32 workstation card - Suffice to say that those 32 machines never had an issue, and eventually, all 800 machines across two rings were transitioned to 100Mb Ethernet. Kindest regards, Doug Jackson em: [email protected] ph: 0414 986878 On Thu, 16 Oct 2025 at 09:12, Wayne S via cctalk <[email protected]> wrote: > Dec was smart about not having single sourced parts. > IBM made their Token Ring chips and therefore controlled the adoption of > parts and network boards for TR. That is one of the reasons Ethernet caught > on while TR did not. I made that argument to management. > > > Sent from my iPhone > > > On Oct 15, 2025, at 14:37, Warner Losh via cctalk <[email protected]> > wrote: > > > > On Wed, Oct 15, 2025 at 12:47 AM Rob Jarratt via cctalk < > > [email protected]> wrote: > > > >> > >> > >>> -----Original Message----- > >>> From: Brent Hilpert via cctalk <[email protected]> > >>> Sent: 14 October 2025 23:14 > >>> To: General Discussion: On-Topic and Off-Topic Posts ( > >> [email protected]) > >>> <[email protected]> > >>> Cc: Brent Hilpert <[email protected]> > >>> Subject: [cctalk] Re: Rainbow H7842 PSU > >>> > >>> On 2025Oct 14,, at 1:42 PM, Rob Jarratt <[email protected]> > >> wrote: > >>>>> -----Original Message----- > >>>>> From: Brent Hilpert via cctalk <[email protected]> > >>>>> > >>>>> There’s some confusion here somewhere. > >>>>> Those input V's would imply the comp. output should be loZ to > >>>>> Vsupply– pin, around –12V; not hiZ, +7.5V. > >>>> > >>>> Oh my! I have clearly got my understanding the wrong way around, not > >> sure > >>> how I did that because I read the datasheet carefully. Somehow, I got > >>> confused. I re-measured and found 1IN+=5.5V, 1IN-=9.4V, Power OK=6.7V, > >> but > >>> GND (on the 393) is -13V. So as you say Power OK should be -13V and AC > OK > >>> H would be asserted. I guess this must mean that the comparator itself > is > >>> faulty. I have some 393s, so I will replace it and see what happens. > >>> > >>> > >>> I don’t think I’ve ever seen a comparator datasheet that explicitly > laid > >> out the > >>> input-to-output function - contrast with other device datasheets with > >> detailed > >>> truth tables galore. > >> > >> I have a Texas Instruments datasheet that does explain it, but much > >> further down in the Application section. I have to say that many > datasheets > >> assume you already know an awful lot about the devices and how they > work, > >> which is definitely not the case for someone like me. > >> > > > > TI is one of the worst for this.Especially if the chip implements an > > industry standard or is compatible with some other chip. In those cases, > > you barely get enough to understand. I've had to many times in the past > > hunt down an industry standard or get the datasheet for the part it's > > compatible with. > > > > DEC was really paranoid about single sourced parts, so just about > > everything is something that's widely used in the industry, and so has > many > > suppliers... You might try that if you're having trouble understanding > the > > datasheet for the exact part. > > > > Warner > > > > > >>> > >>> The comp. datasheets always seem to assume “everybody knows that”. You > >>> can figure it out if you look at some of the example circuits or squint > >> closely at > >>> just the right parameters in the specs and graphs or trace the > operation > >>> through the internal schematic if present. > >>> > >>> In the absence of that, a lot of people seem to (wrongly) assume that > >> “well, + > >>>> – would be 1, so transistor ON”. > >>> > >>> The other way of looking at it, is it’s the 'same direction' of > >> behaviour as an op > >>> amp, but without the upper drive-high output transistor. > >> > >> > >> >
