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Comment by kybernetyk | Hacker News Reader

If it ain't broke, don't fix it.

> The only problem is that the computer operates on the same frequency as some of the walkie-talkies used by the maintenance department.

It's awesome that it's been functional for this long, but given the press attention I hope they don't receive unwanted attention given that this system was implemented in the 1980s, before computer security was as large an issue as it has become.[1]

With the amount of publicity this article has generated, I bet someone with an SDR is going to drive over and analyze the RF signals, and then hijack the HVAC systems for the lulz.

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

Except its in Michigan.

As a Grand Rapids resident who knows quite well how to use a SDR, I'm going to choose a positive interpretation of this comment and assume you're referring to the phenomena of "West Michigan nice", where hacking a public system for lulz would be absolutely unconscionable.

That being said, I'm actually rather tempted to at least figure out what the air interface is. The article mentions a 1200 baud modem - does a standard UHF/VHF voice channel have enough bandwidth to run PSK/FSK V.22 or V.23? That'd be quite a hack.

Very likely it's Bell 202 AFSK. This is specifically designed to run at audio frequencies with 1200 Hz and 2200 Hz tones. You'd have to figure out how the higher protocol levels are implemented but it's probably going to fall within the realm of what is done with AX.25.

I meant that its far the heck away from everywhere and the population is low. Thus, a low incidence of griefers of any kind. But your take is good too.

Two hours from both Detroit and Chicago isn't far. A city of 180,000 isn't low; it's the largest city in the state behind Detroit.

And hey! In a list of US states by population, Michigan is #10! Who knew?!

https://en.wikipedia.org/wiki/List_of_U.S._states_and_territ...

Anyone who has ever been there? I guess unless you flew directly into UP... b^)

Is there an airport up there?

Hey I've been there, and remember endless empty foresty spaces, with some towns every hour or so.

Yep. The Northwest Territory is now home to over 46 million people. Just because it's less dense doesn't make it empty.

If it's about to fail, have a replacement ready.

It's not like an Amiga 3000 or 4000 is that expensive anyway.

And, probably, they could run their software under an emulator, on any US$200 desktop PC.

It's not just the software. They're controlling these systems via radios that operate on the same frequencies as other radios in use. It's (at this point) clumsy and error prone. To be fair, they probably saved the tax payers a lot of money by using this system for as long as they have.

> To be fair, they probably saved the tax payers a lot of money by using this system for as long as they have.

Indeed. The major annoyance I see is the radios interfering with each other. The centralized control architecture is also something I'd like to change. Each building does not require anything much smarter than an Arduino to be completely standalone and, if you want to be fancy, an RPi to send collected data to a centralized location.

Another viable approach could be to setup Amiga emulators on old/discarded PCs and repurpose the existing software using wired instead of wireless connections.

The 2M number is probably a major overhaul of every part of the system. Utility bills alone will probably more than cover the difference.

I suggested a US$ 200 PC because many of those have no moving parts and more storage space than any Amiga ever dreamed of. They should be able to easily last 30 years or more.

Well, at least planning for the future seems prudent. Otherwise if such a system breaks permanently, then you are scrambling to get something else up while the whole system is down (even ignoring the question of backups and data migration to a new system).

Well the article says "If the computer stopped working tomorrow, a staff person would have to turn each building’s climate control systems on and off by hand" - I know that's not exactly a tiny job across 19 schools but it doesn't seem to be a hugely tough task

There can be dozens of air conditioners on the roof of a school. And they have to be cycled on and off all day long as they cool the building, else it'll turn into winter in there. Definitely a fulltime job for somebody. That's why we have thermostats.

You do wonder if those staff people would be ok turning it on and off by hand if they got the "$1.5 to $2 million" needed to replace the system.

That said, I'm pretty sure I could get an Amiga emulator running on a Raspberry Pi for a lot less than $1.5 million.

As has been said multiple times before, it's not $2 million to keep this kid's school project running for another 30 years, it's $2 million for a better HVAC automation system. They've probably pissed away multiples of $2 million in energy costs not having a better system in place the past 30 years.

No kidding, but that's not how the article was written. My second paragraph was a comment on that.

Every budget ever written stuffs things that management thinks can be put off until later into funding for things that absolutely need to be done today.

Often it's dealing with interfaces. A couple years ago I worked at a place with a laser cutter, like an old one. You sent instructions to a program that talked to an interface card, which controlled the cutter. The program ran under DOS. It wasn't possible to replace the OS or machine easily, because it was an ISA card and had custom interface software that relied on having direct access.

If nobody can fix it, break it.

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