[philpem]

The machine itself was made by Convergent Technologies. It's similar to the MiniFrame - and possibly also the MightyFrame.

AT&T rebranded it, and there were two versions: the 7300 can take a single half-height MFM drive, and the 3B1 can take two half-height MFM drives or a single full-height. The 3B1 has a different plastic case with a square-ish 'bump' under the monitor, and usually a modified (called a P5.1) motherboard.

They top out at 4MB RAM (2MB on the motherboard and 2MB on expansion cards). Disk storage would have topped out at 190MB with a single Maxtor XT-2190 full-height, or a pair of Miniscribe 3650s for 2x50 = 100MB.

[lproven]

While I have heard about the 3B1 for years, even if AT&T is an unknown foreign company in my part of the world, I'd never heard of the MiniFrame. Thanks for this.

http://cholla.mmto.org/computers/miniframe/index.html

https://www.computinghistory.org.uk/sec/2963/Convergent-Tech...

The original brochure for the MiniFrame Plus:

https://archive.org/details/bitsavers_convergentmePlusProduc...

A blog about its big brother the MightyFrame, with pics:

http://mightyframe.blogspot.com/

[rbanffy]

Like pretty much everything Convergent did, it was ahead of its time. Some really brilliant people must have worked there. Too bad so few people has hear about them (or used their stuff).

The telltale sign of late Convergent is the keycaps, also present in many Burroughs and Unisys desktops and terminals.