AT&T 7300 / UNIX PC / 3b1

Several kind folks on comp.sys.3b1 and the MARCH Yahoo Group have suggested that, in order for us to gain a better understanding of the workings of the rare and elusive MightyFrame, that we should get familiar with the AT&T 7300 / 3b1.  

Many say that this machine, manufactured by Convergent Technologies for AT&T, is "functionally equivalent to the MiniFrame".  Even though the MiniFrame and the MightyFrame have significant differences, this certainly seems like a great next step for us.

So, our journey continues...

Through multiple system acquisitions, we have been able to assemble one working AT&T UNIX PC.

While the video below shows my failed attempts to login, I did find a universal login that worked.
Thanks to the newsgroup comp.sys.3b1, which has stood the test of time, several individuals had this very discussion back in 1996, when people were still finding uses for these [then] outdated machines.  

Login using install, root, or tutor.  install worked best for me, so I could then choose the administration menu option to remove the root password.  Now I have access to all.
(interesting to note, the final individual to post on that thread STILL replies to my post on that very same newsgroup today, and is quite helpful.  Thanks DoN!)

See the boot up sequence

Working Machine ID Tag

Working Machine #2 ID Tag

Parts Donor Machine ID Tag

Valuable Manuals for this process (links to large PDF files):

AT&T UNIX PC Technical Reference Manual

AT&T UNIX PC Owner's Manual

Visit our rough draft to map the AT&T 7300 motherboard on a website.


We just got a dumb terminal connection to work.  Thanks to Neil at MARCH and DoN at comp.sys.3b1

Using VT100 terminal emulation, and specifying vt100 as the "terminal name" when prompted by the UNIX PC at login seems to work the best.

I had to manually set keys F5-F8 to ^[5 - ^[8 , because for some reason, only F1-4 was functional by default.  

I also had to add special User Buttons for the keys required to control the window menus:
Enter  ^J
Exit   ^[ex
Cancl  ^[cn
Help  ^[?

All escape sequences are listed on PDF page 35 of the AT&T UNIX PC Remote Access User's Guide

-----------------MISCELLANEOUS GENERAL INFO ON THE SYSTEM----------------------------

For reference, here is a AT&T 3B1 Emulator and YouTube presentation has some nice screenshots of the GUI

More helpful reference sites:

Bill Degnan does a nice 7300 vs 3b1 machine comparison on his blog, with links to pictures of his restoration process.

AND, an example of how another one of these boots.  This is not our machine, but someone posted this on YouTube back in 2009.

A goofy retro promo for this machine

I also like this commercial, which slightly pre-dates the 7300
I actually remember it, and I think in 1985 we got a 6300 system, running DOS from floppies with no hard drive.

Maybe I could even buy one today from this MARCH post

And contact chailey666 who says he/she is running a 7300 for fun as of their post below this video around October 2013.


More history?


  1. Anyone know where the TCP/IP software is? I have an ethernet adapter in this 7300, would like to get some stuff off it.

  2. CZ, we have an Ethernet adapter card as well, and I have a full install system that used to run it. Please email me directly at