AT&T Unix PC

The 3B1 (also known as the PC7300, or Unix PC) was a Unix workstation computer originally developed by Convergent Technologies (later acquired by Unisys), and marketed by AT&T in the mid- to late-1980s. Despite the name, the 3B1 had little in common with AT&T's other 3B-series computers.

Hardware configuration

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Exterior of the AT&T 3B1

• 10 MHz Motorola MC68010 (16 bit external bus, 32 bit internal) with custom, discrete MMU
• Internal MFM hard drive, originally 5 MB, later models with up to 67 MB
• At least 512K RAM on main board, expandable via expansion cards
• 3 expansion slots
• Monochrome green phosphor 10-inch (250 mm) monitor
• Internal 300/1200 bit/s modem

PC7300

The initial PC7300 model offered a very limited 512 KB of memory and an extremely slow 5 MB hard drive. This model, although progressive in offering a Unix system for desktop office operation, was painfully slow and had an aggravating 'grinding' noise even when not in active use. The modern-looking "wedge" design was innovative, and in fact the machine gained notoriety appearing in many movies as the token "computer."

AT&T 3B1

A later enhanced model was renamed "3B1". The cover was redesigned to accommodate a full-height 67 MB hard drive. This cover change added a 'hump' to the case, expanded onboard memory to 1 or 2 MB, as well as added a better power supply.

Operating system

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Video of an AT&T PC7300 booting

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AT&T PC7300 compiling and running a C program

The operating system is based on Unix System V Release 2, with extensions from 4.1 and 4.2 BSD, System V Release 3 and Convergent Technologies. The last release was 3.51.

Programming languages

• SMC BASIC
• RM COBOL
• RM FORTRAN
• LPI FORTRAN
• LPI Pascal (programming language)
• LPI C (programming language)
• SVS FORTRAN
• SVS Pascal
• AT&T BASIC
• GNU C++
• LISP

Application software

• SMART System (Office Suite)
• Informix (DBM)
• Oracle (DBM)
• Multiplan (Spreadsheet)

Word processors

• Microsoft Word
• AT&T Word Processor
• Crystalwriter
• WordStar 2000
• Samna Word
• WordMarc
• SMART Word Processor

Games

• Pac-Man
• NetHack
• Chess
• Klondike
• Life
• Mahjongg
• Moria
• Robots
• Rocks
• Rogue
• Tetris

Utility

• HoneyDanBer UUCP package.
• Various Shells: Bourne, C, and Korn
• EMACS
• Kermit
• TeX
• SPICE/NUTMEG (circuit simulation tool)

The Store

The Store is a public domain software repository which was available for all 3B1 users.

Expansion Cards

• DOS-73 8086 co-processor card running MS-DOS, which could be fitted with an 8087 math co-processor chip. This board was designed and built for AT&T by Alloy Computer Products of Framingham MA.
• RAM card could be added using 1 or 2 MB RAM cards (up to a maximum of 4 MB)
• EIA/RAM combo cards contained extra RAM and two RS-232 serial ports.
• Dual EIA port card
• StarLAN 1Mbit/s LAN card
• Ethernet 10 Mbit/s LAN card
• VoicePower card allowed for the capture and digital recording of voice conversations.
• Tape drive card provided interface for 23 MB MFM Tape Cartridge Drive.
• Expansion chassis card was hard-wired to Expansion Chassis (with five added slots)

Networking

• StarLAN – 1 MB/s local area network typically used in star format.

See also

• 3B Computers
• AT&T 6300 Plus
• DEC Professional (computer)
• IBM 6150 RT
• IBM System 9000

External links

• AT&T Leapfrogs IBM WIth the Unix PC., InfoWorld, April 15, 1985, pp. 15–17
• The AT&T Unix PC, article from BYTE magazine Volume 10 Number 05: Multiprocessing (May 1985), pp. 98–106
• comp.sys.3b1 FAQ
• AT&T 3B1/7300 (UNIX PC) Information
• AT&T UNIX PC at old-computers.com
• http://bitsavers.trailing-edge.com/pdf/att/3b1/
• http://www.unixpc.org