Editing 3B series computers (section)

==Microcomputers==
[[Image:3B2_model_400_sitting_on_grass.jpg|thumb|A 3B2 model 400]]

===3B2===
[[Image:3b2-300-motherboard.jpg|thumb|3B2/300 motherboard]]
[[Image:3b2-vme.jpg|thumb|WE 321SB VMEbus Single Board Computer]]

The 3B2 was introduced in 1984 using the [[Bellmac 32|WE 32000]] 32-bit microprocessor at 8&nbsp;MHz with memory management chips that supports [[demand paging]]. Uses include the [[Switching Control Center System]]. The 3B2 Model 300, which can support up to 18 users,<ref name=3Bseries.NYT840328/> is approximately {{convert|4|in|mm}} high and the 3B2 Model 400 is approximately {{convert|8|in|mm}} high.

The 300 was soon supplanted by the 3B2/310 running at 10&nbsp;MHz, which features the WE 32100 CPU as do later models. The Model 400, introduced in 1985,<ref name=unixreviewdec85/> allows more peripheral slots and more memory, and has a built-in 23 MB [[Quarter-inch cartridge|QIC]] tape drive managed by a [[floppy disk controller]] (nicknamed the "floppy tape"). These three models use standard [[Modified Frequency Modulation|MFM]] {{frac|5|1|4}}" hard disk drives.

There are also Model 100 and Model 200 3B2 systems.<ref name=3Bseries.NYT840328/>

The 3B2/600,<ref name=3B2.600NYT870325/> running at 18&nbsp;MHz, offers an improvement in performance and capacity: it features a [[SCSI]] controller for the 60 MB QIC tape and two internal full-height disk drives. The 600 is approximately twice as tall as a 400, and is oriented with the tape and floppy disk drives opposite the backplane (instead of at a right angle to it as on the 3xx, 4xx and later 500 models). Early models use an internal [[Emulex]] card to interface the SCSI controller with ESDI disks, with later models using SCSI drives directly.

The 3B2/500 was the next model to appear, essentially a 3B2/600 with enough components removed to fit into a 400 case; one internal disk drive and several backplane slots are sacrificed in this conversion. Unlike the 600, which because of its two large fans is loud, the 500 is tolerable in an office environment, like the 400.{{Citation needed|date=July 2022}}

The 3B2/700<ref>{{cite news |newspaper=[[The New York Times]]
   |url=https://www.nytimes.com/1988/05/10/business/company-news-at-t-displays-midsize-computer.html
   |title=A.T.&T. Displays Midsize Computer  |quote=could support up to 80 users
   |date=May 10, 1988}}</ref> is an uprated version of the 600 featuring a slightly faster processor (WE 32200 at 22&nbsp;MHz), and the 3B2/1000<ref name=3Bseries.RoyNYT890316>{{cite news |newspaper=[[The New York Times]]
   |url=https://www.nytimes.com/1989/03/16/business/company-news-at-t-addition-to-computer-line.html
   |title=A.T.&T. Addition To Computer Line |date=March 16, 1989}}</ref> is an additional step in this direction (WE 32200 at 24&nbsp;MHz).

===3B1 desktop workstation===
Officially named the ''[[AT&T UNIX PC]]'',<ref name="3B1">AT&T, Select Code 999-601-311IS, ''AT&T UNIX PC Owner's Manual'' (1986)</ref> AT&T introduced a [[desktop computer]] in 1985 that is often dubbed the ''3B1''. However, this [[workstation]] is unrelated in hardware to the 3B line, and is based on the [[Motorola 68010]] microprocessor. It runs a derivative of Unix System V Release 2 by [[Convergent Technologies]]. The system, which is also known as the ''PC-7300'', is tailored for use as a productivity tool in office environments and as an electronic communication center.<ref name="3B1"/>