What's that green glow? Dumb terminal for Raspberry Pi

Your pal Ed Bennett whose Televideo 910 dumb terminal is featured here - is it possible that he might lend a bit of expertise a fan endeavor of ours?

We're looking for any 'dumb' terminal from the 70's or 80's that has the same look as the terminal used on the cover of Kraftwerk's Computer World, one that works and on which we might display ascii art of the band or at least the album cover. It's a fan project. We're specifically buying a Hazeltine 1500 unless a far cheaper option appears.

Likely we can interface any functioning terminal with a Raspberry Pi and a rs-232 serial could talk to it for sure

https://en.wikipedia.org/wiki/Computer_World

In the off chance that I don't see a reply here, feel free to cc us at dsanborn at gmail dot com and THANKS in advance!

Dave

Hi Dave,

Alas, I don't have one of those for you. But I do want to warn you. I started buying USB-RS232 dongles a long time ago. At first they came with MAX232 chips inside. Then with cheap clones and then with... nothing. Apparently if you invert the signals it will usually work for long enough for the complaint-period on ebay to expire.... Now, modern RS232 recievers will have evolved to accept such signals but older hardware has not. So you'll have to search for a "real RS232 signal level" interface to be able to connect the terminal.

Good luck!

Hi Dave,

Alas, I don't have one of those for you. But I do want to warn you. I started buying USB-RS232 dongles a long time ago. At first they came with MAX232 chips inside. Then with cheap clones and then with... nothing. Apparently if you invert the signals it will usually work for long enough for the complaint-period on ebay to expire.... Now, modern RS232 recievers will have evolved to accept such signals but older hardware has not. So you'll have to search for a "real RS232 signal level" interface to be able to connect the terminal.

Good luck!

There's always a 'gotcha' it seems. Some usb-serial converters tout specs like "True 3.3V CMOS drive output and TTL input."

I wonder if pin voltage has any bearing on "real RS232 signal level"?

Do any of these look authentic or usable in your opinion?

This one from Digikey

This one on eBay

This one on Mouser

This CHEAP one on Mouser

If you're curious, this is the Hazeltine we're considering buying on eBay. It's shockingly expensive and I'm sure that more than a few of us IT people have something similar knocking about in our basements or attics for a lot less.

That last one on your list has a schematic in the data sheet. It appears to take +- 25 on the input and +-6.5 typical on the output, those are within the valid RS-232 specs. I can't vouch for the quality, but the description seems to meet the need.

(this one https://www.mouser.com/productdetail/easysync/duoette?qs=sGAEpiMZZMuDw7xUFNwm7IIZz2kfQFNB6Pj0aqNxTFw%3D )

Mike

I agree with Michael: that last one has the specs in hte datasheet and those are "reasonable". Not the 0-5V that I was talking about.

The expensive mouser one, as far as I can see doesn't have the specs we need in the datasheet. That is going to cost them a possible sale.... If its not in the datasheet, don't buy it.

One  Ebay thingy that you linked has just one chip. That's not going tot cut it. If the claim "FT232" chip is correct, then I know that the signal levels are going to be 0-5V that I told you is not a good idea....

The digikey is that same board from ebay, but now from a respected western manufacturer and reseller. But still the same specs I told you to watch out for!

So... Get the cheap one from mouser. :-)

Re: Hazeltine terminal: Well, at least its 30% cheaper than new. :-)

Update: On second reading: You might have been searching for USB-RS232-TTL adapters. You do NOT want to  put in TTL in the search terms: The TTL part means: "we PROMISE you that we left out the level conversion to oldfashioned RS232 levels".