Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1989-08-11
1990-10-23
Miller, Stanley D.
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
328 63, 328104, 328154, 307269, 307243, 307480, H03K 1700, H03K 513, H03K 117, H03K 1756
Patent
active
049655248
ABSTRACT:
Clock select circuitry is provided which allows CPU operation at the crystal frequency or one-half the crystal frequency. Frequency selection is accomplished under CPU control and circuitry is added to insure that the a glitch free clock change can be performed on the fly. The glitch free clock select insures that no half T state is less than what a full speed half T state would be. By gating the appropriate phases of the half speed clock and the full speed clock to control the clocking of a flip flop, the point at which the clock selection multiplexer is switched can be controlled. In speeding up the clock, the speed change occurs on the falling edge of the full speed clock provided that the half speed clock is low. When slowing down the clock, the speed change occurs on the rising edge of the half speed clock.
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Miller Stanley D.
National Semiconductor Corp.
Phan Trong Quang
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