Amdahl UTS

UTS (Universal Timesharing System) is a discontinued implementation of the UNIX operating system for IBM mainframe (and compatible) computers. Amdahl created the first versions of UTS, and released it in May 1981,^[1] with UTS Global acquiring rights to the product in 2002. UTS Global has since gone out of business.

UTS (Universal Timesharing System)
Developer	Amdahl Corporation / UTS Global
OS family	Unix SVR4
Working state	Discontinued
Initial release	May 1981; 44 years ago (1981-05)
Latest release	UTS 4.5
Available in	English
Supported platforms	IBM mainframes (and compatible)
Default user interface	Command-line interface

System requirements

UTS Release 4.5 supports the following S/390 model processors and their successors:

• Amdahl 5990, 5995A, 5995M series of ECL processors
• Amdahl Millennium Global Server series of CMOS processors
• Fujitsu Global Server
• IBM ES/9000/9021 series of ECL processors
• IBM G4, G5 & G6 Servers (the 9672 R and X series of CMOS processors)

History

The UTS project had its origins in work started at Princeton University in 1975^[2] to port UNIX to the IBM VM/370 arrangement. Team members there were Tom Lyon, Joseph Skudlarek, Peter Eichenberger, and Eric Schmidt. Tom Lyon married Amdahl in 1978, and by 1979 there was a full Version 6 Unix system on the Amdahl 470 being used internally for design automation engineering. In late 1979 this was updated to the more commonly ported Version 7.

In 1980 Amdahl announced support for Unix on the System 470.^[3] UTS (Universal Timesharing System) also ran on National Advanced Systems mainframes.^[4] Lyon said at USENIX in June 1981 that Amdahl had run UTS for 370 for two years internally, and unofficially distributed the operating system on request.^[5] Five years later, IBM announced its own mainframe Unix, IX/370, as a competitive response to Amdahl.^[4] The Intel 80386 design team ported UTS to test the processor's viability to run Unix.^[6]

The commercial versions of UTS were based on UNIX System III and UNIX System V. In 1986, Amdahl announced the first version to run bare metal on IBM/370-compatible hardware, UTS/580 for the Amdahl 580 series of machines; previous Unix ports always ran as "guests" under the IBM VM hypervisor. Performance improved by 25% without VM, the company said.^[7] Version 4.5 was based on Unix System V, Release 4 (SVR4).

In 1987 Amdahl announced that it ended Aspen, a project started seven years earlier to create a proprietary operating system, and instead would focus on UTS. The 60 Aspen developers moved to UTS, for a total of 250 Amdahl developers on Unix.^[8] That year the company released version 1.2, and 2.0 in 1989. Version 2.0 supports 31-bit—matching MVS/XA's ability to address up to 2GB of main memory—and Network File System. The upgrade was available for free to the more than 200 customer sites; new customers paid $20,000 for installation. The monthly lease for UTS was $4,000 to $14,000 per month, depending on the customer's processors.^[9]

See also

• Linux on IBM Z
• OpenSolaris for System z
• UNIX System Services in OS/390 and its successors
• UNIX-RT
• RTLinux