GE 645

645
The GE 645 mainframe computer was a development of the GE 635 for use in the Multics project.wikipedia
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Multics

Multics operating systemMultics project
The GE 645 mainframe computer was a development of the GE 635 for use in the Multics project.
It was developed on the GE 645 computer, which was specially designed for it; the first one was delivered to MIT in January, 1967.

Protection ring

kernel modering 0kernel-mode
The GECOS operating system was fully replaced by Multics in 1969 with the Multics supervisor (master mode now known as kernel mode) separated by protection rings with "gates" allowing access from user mode.
The GE 645 mainframe computer did have some hardware access control, but that was not sufficient to provide full support for rings in hardware, so Multics supported them by trapping ring transitions in software; its successor, the Honeywell 6180, implemented them in hardware, with support for eight rings.

Mainframe computer

mainframemainframesmainframe computers
The GE 645 mainframe computer was a development of the GE 635 for use in the Multics project.

Computer

computerscomputer systemdigital computer
The GE 645 mainframe computer was a development of the GE 635 for use in the Multics project.

GE-600 series

GE 635GE-645GE-635
The GE 645 mainframe computer was a development of the GE 635 for use in the Multics project.

Compatible Time-Sharing System

CTSSCompatible Time Sharing System
The original CTSS was implemented on a modified IBM 7094 with two banks of memory and bank-switching between user and supervisor mode.

Multilevel security

Multi-Level SecurityControlled InterfaceMLS
The Multics o/s implemented multilevel security (MLS) on a GE 635 running a simulator of the 645 starting on October 18, 1965 in the MIT Tech Center.

Honeywell

Honeywell InternationalHoneywell CorporationHoneywell, Inc.
A later generation in the form of the 645F (F for follow-on) wasn't completed by the time the division was sold to Honeywell, and became known as the Honeywell 6180.

Honeywell 6000 series

Honeywell 6180Honeywell 6000H-6000
A later generation in the form of the 645F (F for follow-on) wasn't completed by the time the division was sold to Honeywell, and became known as the Honeywell 6180.

Time-sharing

timesharingtime sharingtime-sharing system
The bulk of these computers running time-sharing on Multics were installed at the NSA and similar governmental sites.

Intel 80286

80286286Intel 286
The hardware protection introduced on this computer and modified on the 6180 was later implemented in the Intel 286 computer processor as a four-layer protection ring, but four rings was found to be too cumbersome to program and too slow to operate.

Timeline of virtualization development

Note: This timeline is missing data for important historical systems, including: Atlas Computer (Manchester), GE 645, Burroughs B5000

General Electric

GEGeneral Electric CompanyGeneral Electric Co.
From 1964 to 1969, GE and Bell Laboratories (which soon dropped out) joined with MIT to develop the Multics operating system on the GE 645 mainframe computer.

History of CP/CMS

time-sharing operating systems
IBM had received intelligence that MIT was leaning toward the GE proposal, which was for a modified 600-series computer with virtual memory hardware and other enhancements; this would eventually become the GE 645.

CPU cache

cacheL2 cacheL1 cache
The first documented uses of a TLB were on the GE 645 and the IBM 360/67, both of which used an associative memory as a TLB.