Computer System Designs: System-on-Chip

6

Customization and Configurability

6.1 INTRODUCTION

To broaden SOC applicability while reducing cost, one can adopt a common hardware platform that can be customized to improve efficiency for specific applications. This chapter looks at different customization technologies, particularly those based on configurability. Here configurability covers both one-time configurability, when application-oriented customization takes place once either before or after chip fabrication, and reconfigurability, when customization takes place multiple times after chip fabrication.

Customization opportunities at design time, particularly those exploited in device fabrication, often result in high performance but at the expense of flexibility when the design is deployed. Such postfabrication flexibility is achieved by devices with various degrees of programmability, including coarse-grained reconfigurable architectures (CGRAs), application-specific instruction processors (ASIPs), fine-grained field-programmable gate arrays (FPGAs), digital signal processors (DSPs), and general-purpose processors (GPPs). The trade-off between programmability and performance is shown in Figure 6.1, which is introduced in Chapter 1.

Figure 6.1 A simplified comparison of different technologies: programmability versus performance. GPP stands for general-purpose processor, while CGRA stands for coarse-grained reconfigurable architecture.

Structured ASIC (application-specific integrated circuit) technology supports limited ...