Accession Number:

ADA604004

Title:

Control Implementation for the SPUR Floating Point Coprocessor

Descriptive Note:

Corporate Author:

CALIFORNIA UNIV BERKELEY DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCES

Personal Author(s):

• Jensen, Debby

Report Date:

1987-08-26

Pagination or Media Count:

83.0

Abstract:

SPUR is a RISC-based multiprocessor workstation being designed to facilitate parallel-processing research. Typically, RISC architectures achieve low performance levels for floating-point intensive applications, as the multiple-cycle floating-point instructions are not implemented in the hardware. In an attempt to raise these performance levels, the SPUR system provides floating-point support through an extended instruction set and a tightly-coupled floating-point coprocessor. This report documents the implementation of the control unit for this floating-point coprocessor describing the coprocessor interface, control PLA definitions, the finite state machine, the dynamic cycle counter, the 4-stage load-store pipeline, and the random logic generated to drive the datapath modules. Implementation techniques and trade-offs are discussed including design strategy, area and speed optimization, noise margin considerations, and delay balancing of the datapath control signals for clock skew minimization. Finally, simulation results obtained using SPICE, CRYSTAL, and MOSSIM are presented. The chip is implemented in 2-layer-metal 2 microns CMOS technology, and uses a four-phase non-overlapping clock with a target cycle time of approximately 100ns-140ns.

Descriptors:

• *FLOATING POINT OPERATION
• *MULTIPROCESSORS
• INTERFACES
• PIPELINES
• TRADE OFF ANALYSIS

Subject Categories:

• Computer Programming and Software
• Computer Hardware

Distribution Statement:

APPROVED FOR PUBLIC RELEASE