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Comment by WaitWaitWha | Hacker News Reader

>Turns out that in 1998, SFMTA had the latest cutting edge technology when they installed their automatic train control system.

> "We were the first agency in the U.S. to adopt this particular technology but it was from an era that computers didn't have a hard drive so you have to load the software from floppy disks on to the computer,"

In 1998, most personal computers already had hard drives [0]. From Wikipedia "The IBM PC/XT in 1983 included an internal 10 MB HDD, and soon thereafter, internal HDDs proliferated on personal computers."

The 3.5" floppy is from the mid 80's, again from Wiki [1] "In the early 1980s, many manufacturers introduced smaller floppy drives and media in various formats. A consortium of 21 companies eventually settled on a 3½-inch design..."

[0] https://en.wikipedia.org/wiki/Hard_disk_drive

[1] https://en.wikipedia.org/wiki/Floppy_disk

Why do I have to do this research instead of the "journalist"?

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Why would a hard drive be better? If the floppy fails just grab another off the shelf and try it (surely they have more than one copy). Downtime measured in seconds.

The other good thing about the floppy is it can't hold very much code. So the system has a tight upper bound on how bloated and complex it can get. Simpler systems are more maintainable.

These things seem like great assets for maintaining critical infrastructure.

EDIT: Another great thing is such a system will be stateless. No disks, no filesystems, no databases. Sign me up.

While nothing you've said is wrong, that's not their point.

(These days, you could also replace the floppy with a USB drive: they make adapters/emulators.)

He never said it was better. He's pointing out glaring factual errors in the story.

Where is the factual error? This passage is the one we're taking about right?

> Turns out that in 1998, SFMTA had the latest cutting edge technology when they installed their automatic train control system.

The fact of when hard drives became commonplace in personal computers (EDIT: or when 3.5" floppies were introduced) has no bearing whatsoever on whether this transit control system was cutting edge in 1998. This statement is not, at least not obviously, factually incorrect. So if you're going to claim that, show your work.

I have this feeling that they meant 1988 instead of 1998....but I could be wrong?

Edit: Even the news article hints at 5 inch floppy disks...which makes 1998 make absolutely no sense to me at least.

https://abc7news.com/san-francisco-train-system-has-been-run....

I'm not sure moving it back a whole decade saves them?

My family's first PC in 1987 had a hard disk. The Wikipedia quote they provide lines up with that, and provides a more authoritative point of when it was introduced.

And yeah, the "5 inch floppy" quote paired with a photo of a diskette. God only knows what actual hardware the system uses. But point being … the journalist doesn't seem to have found out.

There's a big difference when choosing technologies for a home computer versus a safety-critical system that will run for decades. Seems reasonable they would've chosen a proven, if slightly outdated, tech over a newer one that had less data to back up its long-term reliability.

And of course we can get into the discussion of cost: floppies are way cheaper than hard drives, especially for the presumably-small amounts of data that are needed for such a control system. A 500MB hard drive was probably overkill.

I am of course speculating, but I don't know why we should assume that the engineers working on the project originally made a silly decision. They almost certainly weighed the available options to deliver the project within the defined constraints of the system.

Hard drives weren't new in 1998. I don't even know where you'd have gotten a computer that lacked one by then; and most would also have had a CD-ROM drive.

The Mac SE had a 20 MB hard disk in 1987! And there was no way Windows 95--which everyone had by 1998--was fitting on a floppy of any size.

Many computers in the late 1980's came with hard disks, but the cheapest ones did not.

Yeah, on further reflection, I recall my parents having a 286 with a hard drive. Still don't get why they couldn't find a 5.25" floppy. Then again both types of floppy drives are still quite obsolete....

  Why do I have to do this research instead of the "journalist"?

Ratchet the snark back. The journalist was referring to the train control system not home computers in someone's basement. And, yes, twenty five years ago SelTrac was cutting edge. Moving block systems were basically unheard of back then.

The only snark here is yours. What are you talking about with "computers in someone's basement?"

He pointed out glaring factual errors in the story, which should not have made it through any kind of editorial review. For example: 25 years ago pretty much every computer had a hard drive. And the disk depicted in the article is obviously a 3.5", not a "five-inch floppy."

Whether the computer in your basement had a hard drive or not has no bearing on whether or not SelTrac was cutting edge at the time (it was). That there were even computers with microprocessors put SelTrac decades ahead of what was in use elsewhere at the time.

> glaring factual errors

You keep parroting this maxim without showing any convincing evidence of an error... what's the point of that? You obviously have some affinity for factual correctness, yet your style of argument and evidentiary rigor appears to boil down to "repeating the maxim many times in many different places makes it more factually true" which is obviously nonsense. Maybe some food for thought?

> And, yes, twenty five years ago SelTrac was cutting edge. Moving block systems were basically unheard of back then.

Meanwhile in Germany, we have had moving blocks from the late 80s, based on a technology developed from the mid-60's and production-ready by the 70s [1]. Incredibly, the LZB technology never had an actual accident happen in all the time, only three "bare misses" (one of which was pretty spectacular in that it caused a train to pass over a switch rated for 80 km/h with around 185 km/h without derailing).

[1] https://de.wikipedia.org/wiki/Linienf%C3%B6rmige_Zugbeeinflu...

SelTrac has been around since the mid 80s, and was originally a German developed product (Standard Elektrik Lorenz) based on LZB technology.

My understanding of LZB is limited, but it appears to be a fixed block system with wayside detection of trains, albeit with shorter blocks than lineside signals would usually have. This is different to SelTrac which is moving block.

Yeah, LZB internally is based on fixed blocks - but on a system with block lengths down to 50 meters (as in the Stammstrecke München [1]), the difference is negligible.

Crazy to see that SelTrac was actually developed in Berlin, failed there, but is still in widespread use across the world.

[1] https://de.wikipedia.org/wiki/Stammstrecke_(S-Bahn_M%C3%BCnc...

Given that the agency seems not to be able to cope with change at a reasonable pace, I wonder if 1998 was just when the control system project finished, having been planned and started several years prior.

> I wonder if 1998 was just when the control system project finished, having been planned and started several years prior.

Probably this. Probably they got the plans worked up in 1990, but didn't finish everything until 1998.

I'd say they must have started closer to 1980. By the time we had the 286, most PCs came with a hard drive, and 1990 was the era of the 486.

I had the displeasure to operate a sort of industrial/automotive rack computer running very simple Simulink data logging that booted only from a floppy, and I think it was bought around 2008. For a greenfield project.

Probably cost like hell and was decade or two behind in technology, but I didn't buy it and definitely wouldn't have. Salespeople get people to do stupid stuff.

I'd guess these are used a lot in industrial settings where the code and task is actually very simple. Would run no problem with a $1 microcontroller and a hundred lines of C and with a lot less hassle. Likely vendors have gotten a reputation and keep on selling them with FUD.

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