Signetics 2650

The Signetics 2650 was an 8-bit microprocessor introduced in July 1975. According to Adam Osborne's book An Introduction to Microprocessors Vol 2: Some Real Products, it was "the most minicomputer-like" of the microprocessors available at the time. A combination of missing features and odd memory access limited its appeal, and the system saw little use in the market. In 1972, Signetics' Jack Curtis hired John Kessler of IBM to lead the design of a new single-chip CPU intended to compete with minicomputer systems. Kessler selected the IBM 1130 as the model for the new design. The 1130, released in 1965, was a 16-bit minicomputer that shared many design features with other minis of the era. While Kessler designed the architecture, Kent Andreas laid out the CPU using a recently developed ion implantation NMOS process. In contrast to the far more common PMOS process of the era, NMOS used less power and dissipated less heat. This allowed the chip to be run at higher speeds than PMOS CPU designs, and the first 2650's ran at the same 1.25 MHz speed as the contemporary models of the 1130. When it was designed in 1972, the 2650 was among the most advanced designs on the market, easily outperforming and out-featuring the Intel 4004 and 8008 of the same era. In spite of this, the design was not released to production. At the time, Signetics was heavily involved with Dolby Laboratories, developing integrated circuits that implemented Dolby's suite of noise-reduction systems. Production of the 2650 was pushed back, and the CPU was not formally introduced until July 1975. By 1975, several new CPUs had been introduced, designed from the start to be 8-bit machines rather than mimicking an older design, and the 2650's advantages were no longer as compelling. In 1975, Philips purchased Signetics, and from that point versions of the 2650 can be found with both Signetics or Philips branding. In March 1976, Signetics reached a second-source agreement with Advanced Memory Systems (AMS).