Field Programmable Gate Array (FPGA) technologies enabled the implementation of customizable computing platforms using System-on-a-Programmable-Chip (SOPC), where we can configure hardware resources appropriately to match specific application needs. In this paper, a new system design concept and a system design flow are proposed for SOPC paradigm. We describe our design and implementation of an embedded system on an SOPC development board, comparing different design methodologies and implementations using FIR application. Using the proposed design flow, the development cycle can be surprisingly short and the flexibility of SOPC can make us achieve the design specification effectively.