GE-200 series

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The GE-200 series was a family of small mainframe computers of the 1960s, built by General Electric.

The main machine in the line was the GE-225. It used a 20-bit word, of which 13 bits could be used for an address. Along with the basic CPU the system could also include a floating-point unit, or interestingly, a fixed-point decimal option with three 6-bit decimals per word. It had 11 I/O channel controllers, and GE sold a variety of add-ons including disks, printers and other devices. The machines were built using discrete transistors, with a typical machine including about 10,000 transistors and 20,000 diodes. They used core memory, and a standard 8k-word system held 186,000 magnetic cores.

The GE-215 was a scaled-down version of the GE-225, including only 6 I/O channels and only 4K or 8K of core.

The GE-235 was a re-implementation of the GE-225 with three times faster memory than the original. ^[1] The GE-235 consisted of several major components and options:

Central processor
400 CPM or 1000 CPM card reader
100 CPM card punch or 300 CPM card punch
Perforated tape subsystem
Magnetic tape subsystem
12 Pocket high-speed document handler
On-line high speed printer or Off/on-line speed printer
Disc storage unit
Auxiliary Arithmetic Logic Unit (ALU)
DATANET data communications equipment

Through the early 1960s GE worked with Dartmouth College on the development of a time-sharing operating system, which would later go on to become Dartmouth Time Sharing System (DTSS). The system was constructed by attaching a number of teletypewriters to a smaller GE machine called the Datanet-30, which was a small computer that had evolved from an earlier process-control machine.

DTSS was an odd system; it didn't run on the GE-235, but the DN-30 instead. The DN-30 accepted commands one at a time from the terminals connected to it, and then ran their requested programs on the GE-235. The GE-235 had no idea it was not running in batch mode, and the illusion of multitasking was being maintained externally. This represents an interesting stage in the evolution of multitasking.

In 1965 GE started packaging the DN-30 and GE-235 systems together as the GE-265. The GE-265 achieved fame not only for being the first time-sharing system, but it was also the machine on which the BASIC programming language was first created.