Sun Microsystems, Inc.

Steven M Kurihara

Mark W Insley

Ewa M Kubalska

Abraham E Rindal

Charles Patton

A circuit for outputting area pattern bits from an area pattern array. The circuit includes a first stage, second stage and third stage. The first stage is configured to output N adjacent scan lines from a 2N&#xd7;2N area pattern array based on a first address. N is a positive integer. The second stage is configured to receive the N adjacent scanlines and to select an N&#xd7;N block from the N adjacent scanlines based on a second address. The third stage is configured to (a) select an (N/2)&#xd7;N region of bits from the N&#xd7;N block and load bits of the (N/2)&#xd7;N region into a set of pixel tag outputs in a first mode, and (b) select an N&#xd7;(N/2) region of bits from the N&#xd7;N block and load bits of the N&#xd7;(N/2) region into the set of pixel tag outputs in a second mode.

Area pattern processing of pixels

A merge unit for the merging of tiles or arrays of pixels or samples, and suitable for use in a high performance graphics system is described. The unit may improve the utilization of memory bandwidth by combining non-intersecting tiles of pixels, and hence potentially reducing the number of storage operations to the memory.

Graphics fragment merging for improving pixel write bandwidth

A computer system including a central processing unit (CPU) and a power management circuit (PMC). The CPU has an active mode where it is responsive to interrupt and direct memory access requests, and a standby mode where it is in a low power state and is not responsive to the interrupts and direct memory access requests. The PMC monitors the interrupts and direct memory access requests in the system when the CPU is in the standby mode, and causes the CPU to enter the active mode upon the detection of either an interrupt or a direct memory access request. The PMC includes: a standby register having a content which indicates either a standby or an active mode for the CPU; logic coupled to the standby register to produce a standby enabling output signal when the content of the standby register indicates a standby mode, and to produce a standby disabling output signal when the content of the standby register indicates an active mode; and logic which forces the content of the standby register to the active mode upon the detection of either an interrupt or a direct memory access request. A method for managing power consumed by a CPU of a computer system includes forcing the CPU to enter a low-power standby mode, monitoring the computer system for interrupts and direct memory access requests, and reactivating the central processing unit to an active mode where the CPU is capable of responding to the detected requests.

Method and apparatus for reducing power consumption in a computer system

Electromagnetic interference ('EMI') generated by a flat panel video display system is reduced by periodically phase/modulating the panel clock. This spreads EMI energy associated with each panel clock harmonic by a frequency amount .DELTA.f proportional to the rate of phase change in the panel clock signal. EMI energy associated with each panel clock harmonic is reduced relative to a square-wave panel clock signal because the same energy is now spread over a group of frequencies centered about each harmonic. The phase of the panel clock is changed at a rate exceeding the bandwidth f.sub.m of a standard EMI measurement reference window. This disperses adjacent spectral energy sufficiently so the reference window measures but one, decreased, amplitude at a time. Phase-modulation may be achieved using a clock pulse dropping circuit that receives a square-wave input of frequency Nf.sub.c from a main oscillator, drops at least one clock pulse out of a stream of M clock pulses, and frequency divides the resultant waveform by N. The resultant panel clock will have two phases, wherein rate of phase change .DELTA.f is Nf.sub.c /2M. The spectral spacing .DELTA.f of sidebands around each harmonic in the EMI spectrum changes as a function of .DELTA.f. Measured EMI is reduced when .DELTA.f=Nf.sub.c /2M&gt;f.sub.m.

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Palo Alto, CA, United States of America

Steven M Kurihara