A 28 mW/MHz at 80 MHz structured-custom RISC microprocessor design is described. This 32-b implementation of the PowerPC architecture is fabricated in a 3.3 V, 0.5 /spl mu/m, 4-level metal CMOS technology, resulting in 1.6 million transistors in a 7.4 mm by 11.5 mm chip size. Dual 8-kilobyte instruction and data caches coupled to a high performance 32/64-b system bus and separate execution units (float, integer, loadstore, and system units) result in peak instruction rates of three instructions per clock cycle. Low-power design techniques are used throughout the entire design, including dynamically powered down execution units. Typical power dissipation is kept under 2.2 W at 80 MHz. Three distinct levels of software-programmable, static, low-power operation-for system power management are offered, resulting in standby power dissipation from 2 mW to 350 mW. CPU to bus clock ratios of 1/spl times/, 2/spl times/, 3/spl times/, and 4/spl times/ are implemented to allow control of system power while maintaining processor performance. As a result, workstation level performance is packed into a low-power, low-cost design ideal for notebooks and desktop computers. >

A 2.2 W, 80 MHz superscalar RISC microprocessor

Somerset Design Center he 604 microprocessor is the third member of the PowerPC family being developed jointly by Apple, IBM, and Motorola. Developed for use in desktop personal computers, workstations, and servers, this 32-bit implementation works with the software and bus in the PowerPC 601 and 603 microprocessors.‘m3 While keeping the system interface compatible with the 601 microprocessor, we improved upon it by incorporating a phase-locked loop and an IEEE-Std 1149.1 boundary-scan QTAG) interface on chip. In addition, an advanced machine organization delivers one and a half to two times the 601’s integer performance.

The PowerPC 604 RISC microprocessor.

The PowerPC 603 incorporates a variety of features to reduce power dissipation: dynamic idle-time shutdown of separate execution units, low-power cache design, and power considerations for standard cells, data-path elements, and clocking. System-level features include three software-programmable static power management modes and a hardware-programmable phase-lock loop. Operating at 80 MHz, the 603 typically dissipates 2.2 W, while achieving an estimated 75 Specint92 and 85 Specfp92. >

PowerPC 603, a microprocessor for portable computers

A multiply-add unit includes a digit alignment shift number and exponent generator unit, an addend digit alignment and sign adjusting unit, a multiplier array, a sticky-bit for addend lower digits generator unit, a leading digit detector unit, a carry propagate adder, an exponent normalizing unit, an addend higher digit incrementer, a sticky-bit generator unit, a normalizing shifter, a positive number conversion and rounder unit, and an exponent correction unit. The multiplier array is an array of carry save adders. The leading digit detector unit receives the two terms of carry and sum parts from the multiplier array, sequentially checks a digit pair of "0" to "1" at each corresponding digit position from the highest digit, and detects the leading non-zero digit of the absolute values depending upon what digit pair values are (11, 00, 10, 01) from higher to lower digit position.

Multiply-add unit and data processing apparatus using it

The PowerPC 620 RISC microprocessor is the first chip for the application server and technical workstation product line within the PowerPC family. It utilizes a high performance microarchitecture with many advanced superscalar features to exploit instruction level parallelism. It is the first 64-bit implementation of the PowerPC architecture supporting both 32- and 64-bit application software, and is compatible with the PowerPC 601, PowerPC 603, and PowerPC 604 microprocessors.

The PowerPC 620 microprocessor: a high performance superscalar RISC microprocessor

The PowerPC 603 microprocessor is the second member of the PowerPC microprocessor family. The 603 is a superscalar implementation featuring low power operation of less than 3 watts while maintaining high performance of 75 SPECint92 (estimated) at 80 MHz. The 7.4 mm by 11.5 mm design is implemented in 0.5 /spl mu/m, four-level metal CMOS technology. The 603 features dual 8-kByte instruction and data caches and a 32/64-bit system bus. Peak instruction rates of 3 instructions per clock cycle give outstanding performance to notebook and portable applications. >

S. Mallick

Papers

The PowerPC 603 microprocessor: a high performance, low power, superscalar RISC microprocessor