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AT&T Personal Terminal 510A


Veteran Member
Oct 22, 2008
Kamloops, BC, Canada
Here we go. Another case of Mysterious Hardware from the 80's.
So in the early 80's while AT&T was cranking out Unix PC's and PC6300 clones one of the neglected corners of their R&D lab decided to build a terminal for the home or the office desk. Obviously they ended up never being a commercially viable product and after a few years of poor sales they were withdrawn and have pretty much vanished from existance. It seems all that remains now are a few scant magazine articles that google lists, a thread here on this forum and a few low resolution images in Google Images.
I never actually crossed paths with mine. Someone on my regular IRC channel mentioned he saw one at a Goodwill down in Austin, TX. Because I was about to visit Seattle and thus bypass over-the-border shipping fees I sent him enough money to buy it and pack it as damn well as my money could to by buddy's house.





It's a strange little terminal. All-plastic design with a 9" CRT on top, plus the following:

-Dual line capable POTS/Merlin* telephone with speakerphone
-Integrated 300/1200bps modem
-Optional keyboard
-Monochrome 9" CRT with SoftTouch
-User interchangeable option modules
-EIA/RS-232 connector for external serial devices
-Battery backed memory
-Integrated address book, calculator, calendar, clock and VT100 compatible terminal emulation

*Digital option on 510D series units only

While mine is totally missing the handset which I have been told is exactly like an ivory handset found on a Merlin the one thing you can't lose or ignore is the touchscreen.



This is perhaps the weirdest touchscreen technology I have ever encountered. It feels absolutely alien. Using it and the menu system you could use the terminal without the need for a keyboard, which is nice as it doesn't seem to take your standard keyboard.


In that close-up you can also see the connection for the second telephone connection. The unit ships with a plastic insert fitted over it.
The only other connectivity you can get out of the unit is through the cartridge slot.


It faces the back of the machine however pivots upwards so you can more easily swap modules and that I can seem to find that there were three different modules made before development was abandoned, or at least those are the only ones that survived to be scraped by Google.

-"Teach me", the basic cartridge that every unit came with apparently.
-"Directory", presumably an enhanced phone book?
-"Password", I got no idea on this. either it's a hard-coded security device or some sort of way to apply a higher level of security than the unit normally offers.

The Teach Me cartridge is fairly simple inside. The PCB with an edge connector and a single TMS47250 MOS Static ROM.



Now that's about it on the outside. Now it's time to crack it open.
Disassembly isn't anything interesting however it's interesting to note that under the grille on the front where you would expect the speaker for the speakerphone there's a circular ring and nothing. There is no speaker here. Likewise all the buttons on the front share a large PCB separate from the main logic board. Both sides of the board is covered in a grid of square pads but not in any arrangement that would hint that this would of been for a possible keyboard inside the unit. After fiddling with some cables and a lot of tinfoil grounding straps you will release the logic board.


It occupies all available space inside the unit and is powered by a good old Zilog Z80A microprocessor. Present also is the various Zilog support logic like the SCC and more Texas Instruments ROM chips. In the upper left is where the 3V lithium battery lived. Even after over 35 years of life it had only dropped 0.1v but regardless it was removed.


The power supply on this unit was an obvious retrofit. While not original it looked quite professionally substituted.


Unfortunately we now come to the part where I explain why I can't actually show the cool touch screen driven UI. While it was indeed EXTREMELY well packaged, the CRT didn't survive.
It wasn't necked and as we can see the monitor from the outside wasn't damaged at all. Yet somehow the base of the tube managed to shatter.




Inside the monitor housing is a retrofit speaker for the speakerphone, plus the analog board and sandwiched between the front bezel and the CRT is the gel touchscreen membrane and a fine anti-glare mesh. The tube itself thankfully separates from everything easily enough and reveals it was a Zenith 9ATK10, manufactured on September 16, 1985. I can find no datasheet for the thing so while 9" monochrome tubes aren't exactly rare (EG: any compact mac, ciz there's a lot of donor machines out there) the odds of finding a direct replacement are not likely. A substitute could be made to work possibly with a repinning of the socket which itself would require the pinout of the original tube.

So there we have it. We're far from a working unit at this point but it was still exciting regardless to photograph the crap out of it. I do hope someone finds it insightful.