A circuit for transmitting a block of data is disclosed. The circuit comprises a memory array having a plurality of memory locations coupled to receive data; a first data source coupled to the memory array, wherein data from the first data source is stored at sequential addressable memory locations of the plurality of memory locations on a first in, first out basis; a second data source coupled to the memory array, the second data source providing data to be stored in a predetermined memory location of the sequential addressable memory locations storing data from the second data source; and a selection circuit coupled to the first data source and the second data source for selecting data to be stored in the plurality of memory locations.