A 3 . 8 ms

We describe the use of a reconngurable interface board based on FPGAs and a UNIX workstation to implement a correlation tracker with 3.8ms latency. The correlation tracker is part of an active mirror system in use at the The reconngurable interface is used to leverage the workstation CPU, relieving it of tasks that it performs poorly such as rapid context switching and low-level bit manipulation. The reconngurable interface handles control of external devices, high-performance input (16 MB/s) and data preformatting. The workstation CPU, a 64-bit microprocessor, performs the bulk of the computation. For the key computations of the correlation tracker we are able to treat 8 pixels in parallel in the CPU's 64-bit integer datapath. We present the structure of the CCD interface connguration and the implementations of the key algorithms on the workstation CPU. We describe the design trade-oos that arose during the development of the system, and demonstrate the symbiosis between components implemented in software and conngurable hardware.