Old PC Technology

[ila]

Originally Posted by a9127

ila,

75 baud? I believed you but had to look it up. It looks like those speeds were used with "teletypewriting" or TTY (mainframe terminals?). I have seen that term "TTY" used with Modems. Don't remember if I ever set anything for that. Maybe for CompuServe? The slowest I've ever used was a "VIC Modem" which was 300 baud. Blazing fast for the time. At least you could get "on line."

Yep, 75 baud was teletype. It was analogue communications though and not digital. The method of transferring data is somewhat similar except that analogue communications usually measured the voltage level, which varies according to the character being transmitted, whereas in digital the voltage is either on or off.

[a9127]

Up early today to work with my students online. Taking a break. Don’t exactly know where to post this. Since it features old technology of the day, I will place it here. Today is April 1st.

April 3, 1974 was a very bad day for weather in the United States. Almost 150 tornadoes in 24 hours. Many lives lost. A record that would not be broken until 2011.

Anyone remember it? Probably most of us weren’t around yet. But if you live in the Central US you most likely know someone who survived it. I am from Detroit. On the map, you can see there is one tornado (#30) that went between Michigan and Canada. I think it crossed over into Windsor in Ontario and caused damage there. Not sure, I wouldn't be born until the 80's.

Members of my family remember this day however. Both my parents remember it although they hadn’t met yet. We are all “West Siders” so I don’t know how bad it actually was where they lived but there were tornado watches and warnings issued for lower Michigan and Canada.

Ironically, the location in Indiana where I live today, appears to have been “spared.” Monticello Indiana did not fare so well. The city took a direct hit from an F4 or F5 tornado that caused great devastation and loss of life. That's the long track in Northern Indiana (#12 and #13). I knew 2 people at Purdue who survived this tornado. Very young then, they both lost their homes and told me they thought they were “going to die.” One remembers his mom covering him under a table as their house was torn apart.

In Southern Indiana, Hanover College was destroyed. The tornado, an F5, then headed straight for Madison, an historic city along the Ohio river and popular vacation destination. At the last second, it changed course. My current wife and also my “ex” have spent lots of time visiting Madison. It’s a popular vacation destination in Indiana. And they have powerboat races on the Ohio. Check out the movie “Madison.” Belterra Resort and Casino, today, is not far from there. This picture of the tornado is posted in many places around town. I have also visited Hanover College. Some signs of the devastation remain today.

But perhaps the story most people have heard was about the Xenia, Ohio tornado. Striking late in the afternoon. It killed over 30 people when it hit a subdivision around dinner time. It is known in popular culture as the tornado that threw a school bus onto the stage. Not an urban legend, this really happened. Students had been rehearsing for a play when one looked out a stage door and saw the approaching tornado. They all took cover. You can see what happened to the school below.

The technology of the time included radar (based on WWII technology—no Doppler then), early satellites, and “teletype” machines. Most warnings went out over radio or TV. Some too late…

(This “outbreak” is legendary in the United States. And there are many people still alive who will never forget that day. I wonder if "Dr. Amy" was born yet? I think she looks too young. Right now it’s in the 30’s F here. So today we are most likely to get snow… We have our own problems right now with the coronavirus… Stay well!)

[ila]

Originally Posted by a9127

...The technology of the time included radar (based on WWII technology—no Doppler then)...

Doppler just means the change in frequency between the transmitted signal and the received signal. All radar does and always has worked by the Doppler effect.

The difference between early radar and modern versions is the quality of the receiver/computer that can process the returned signal. Modern radar is able to get more and better detail than the old analogue vacuum tube radar.

[a9127]

Originally Posted by ila

Doppler just means the change in frequency between the transmitted signal and the received signal. All radar does and always has worked by the Doppler effect.

The difference between early radar and modern versions is the quality of the receiver/computer that can process the returned signal. Modern radar is able to get more and better detail than the old analogue vacuum tube radar.

What about the rest of my post?

I know what the "Doppler Effect" is. And how radar works. I was under the impression that the radar standard used for years (in the US at least) was WSR-57 and produced images like the one I included in my post above. The Xenia Ohio tornado was indicated by the "hook" echo which must have come from the Doppler effect. Weather radar today uses a different, upgraded standard introduced in 1988 known as "WSR-88." From what I've read, these can measure motion or "rotation" inside a thunderstorm and identify cells that might produce a tornado.

Some of the old "WSR-57's" lasted into the 90's. I read somewhere that Hurricane Andrew in 1992 blew one of the last operational ones off the roof of a weather station in Florida.

The site is all yours my friend... I have contemplated leaving many times. Guess it's time.

[ila]

The whole purpose of my post was to dispel the misconception some people have that Doppler radar is something new or something special. I was merely stating, for those interested, what Doppler means. My post was meant to convey the fact that radar since its inception has worked on the Doppler effect. The main difference now is in the signal processing capabilities of equipment whereby more information can be gathered. My post in no way was to insinuate that you did not understand what is the Doppler effect or how radar functions.

[a9127]

Did not know this font had been around for over 60 years. The slide show accompanying the article is interesting. No wonder it seems like it is everywhere…

https://www.cnn.com/style/article/he...ars/index.html

(Below is an Apple “Mac” circa 1984. My current students think dinosaurs roamed the earth back then. )

[a9127]

How many of you owned one of these? Although we had Macs like the one above in school, my “first” Mac was this one. A “Biondi Blue” model purchased in 1999. If I remember right you could get them in at least 5 colors.

I also opted for the 3 ½” external floppy drive which connected through a USB interface. Steve Jobs did not want anyone to use “floppies” as he envisioned an interconnected world via the “Internet” (quotes because back then it was a still a “thing”… ). But as you can see, there still are wires! And a small CRT display. Wonder what was up with that? Just a few years later that would all change.

It came with a “Jurassic Park” style game. I also had Microsoft Office for it so I could use Excel, Word, and PowerPoint. “Nanosaur” was released April 6, 1998. And an update was offered in 2002 (Nanosaur Extreme). My nieces would probably like Nanosaur. Too bad my iMac ended up in a landfill many years ago.

I still have the 3 ½” floppy in my office… just in case. It has come in handy. My current students have never even used one.