GE-600 Series - History

History

The GE-600 line of computers was developed by a team led by John Couleur out of work they had done for the military MISTRAM project in 1959. MISTRAM was a tracking system that was used on a number of projects (including Project Apollo) and the Air Force required a data-collection computer to be installed in a tracking station downrange from Cape Canaveral. The data would eventually be shared with the 36-bit IBM 7094 machine at the Cape, so the computer would likely have to be 36-bits as well. GE built a machine called the M236 for the task, and as a result of the 36-bit needs, it ended up acting much like the 7094. In fact GE offered a box to connect to the 635 called a 9SA that allowed the 635 to run 7094 programs.

GE originally hadn't intended on entering the commercial computer market with the machine. However by the early 1960s GE was the largest user of IBM mainframes, and producing their own machines seemed like an excellent way to lower the costs of their computing department. In one estimate the cost of development would be paid for in a single year free of IBM rental fees. Many remained skeptical, but after a year of internal wrangling, the project to commercialize the M236 eventually got the go-ahead in February 1963.

The machine was originally offered as the main GE-635, and the slower but compatible GE-625 and GE-615. While most were single processor systems, the 635 could be configured with four CPUs and up to four input/output controllers (IOC's) each with up to 16 Common Peripheral Interface Channels.

The 635 was likely the first example of a general purpose SMP system, though the GECOS/GCOS software treated the processors as a master and up to three slaves. The 600 line consisted of six models: the 605, 615, 625, 635, 645, and 655.

The 615 was a 635 with Control Unit (CU) and Operations Unit (OU) overlap disabled, and a 36 bit wide memory path. The 625 was a 635 with Control Unit and Operations Unit overlap disabled and 72 bit wide memory path. The 635 had a 72-bit wide memory path and CU/OU overlap enabled. The difference between these models was less than 10 wires on the backplane. Field service could convert a 615 to a 635 or 625 or vice versa in a couple of hours if necessary;other than those few wires, the 615, 625 and 635 were identical. The 605 was used in some realtime/military applications, and was essentially a 615 without the floating point hardware. Programs coded for a 605 would run without any modification on any other 600 line processor

The 645 was a modified 635 processor that provided hardware support for the Multics operating system developed at MIT. The 605/615/625/635 and 645 were essentially 2nd Generation Computers with discrete transistor TTL logic and a handful of integrated circuits. Memory consisted of a two-microsecond ferrite core, which could be interleaved. GE bought core memory from Fabri-Tek, Ampex and Lockheed. The Lockheed memory tended to be the most reliable.

The last model, the 655, was announced but probably never delivered as a 655.

Continuing problems with the reliability of the magnetic tape systems used with the system cast a pall over the entire project. In 1966 GE froze many orders while others were cancelled outright. By 1967 these problems were cleared up, and the machines were re-launched along with an upgraded version of the GECOS operating system.

A follow-on project to create a next-generation 635 started in 1967. The new GE-655 replaced the individual transistors from the earlier models with integrated circuits, which doubled the performance of the machine while also greatly reducing assembly costs. However the machine was still in development in 1969, by which time the Multics project had finally produced an operating system usable by end-users. Besides MIT, Bell Labs, and GE, GE-645 systems running Multics were installed at the US Air Force Rome Development Center, Honeywell Billerica, and Machines Bull in Paris. These last two systems were used as a "software factory" by a Honeywell/Bull project to design the Honeywell Level 64 computer.

GE sold its computer division to Honeywell in 1970, who renamed the GE-600 series as the Honeywell 6000 series. The 655 was officially released in 1973 as the Honeywell 6070 (with reduced performance versions, the 6030 and 6050). An optional Decimal/Business instruction set was added to improve COBOL performance. (Extended Instruction Set, aka EIS and the Decimal Unit or DU). The machines with EIS were the 'even' series, the 6040, 6060, 6080 and later the 6025. Several hundred of these processors were sold. Memory was initially 600 ns Ferrite core made by Lockheed. Later versions used 750 ns MOS memory. The two could co-exist within a system, but not within a memory controller.

A version of the 6080 with the various Multics-related changes similar to the 645 was released as the 6180. A few dozen 6180-architecture CPUs were shipped. Later members of the 6000 series were released under various names, including Level 66, Level 68, DPS-8, DPS-88, DPS-90, DPS-9000 by Honeywell, Groupe Bull, and NEC.