GE-200 Series

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. 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.

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 commercially successful time-sharing system, but it was also the machine on which the BASIC programming language was first created.