ram 402 the incoming data is aligned in receive aligner 404 pacman 302 is operable to pack that data in an associated pacram 306 upon receipt and correspondingly retrieves and unpacks the packed data stored in pacram 306 for transmission the data retrieved and unpacked by pacman 302 is aligned for transmission in transmission tx aligner 406 and then stored in transmit first in first out ram tx fifo ram 410 to await transmission each port on the communications device managed in accordance with the memory management scheme of the present invention has an associated portion of pacram 306 where packed data received through that particular port is stored fig5 shows six registers associated with the operation of pacman 302 these registers include pack register p 602 input register 604 output register 606 store register 608 fetch register 612 and update register 610 in storing and retrieving data pacman 302 uses a buffer occupancy scheme as opposed to a round robin or fan out method in that since pacman 302 data from varying sized frames equal time slots of service cannot be given to each port instead a comparison method is used to determine which channel or channels have data to process thus the registers implement a burst based memory returning to fig2 pacman 302 stores received frames of data in 128 byte blocks of cache like memory each frame having an associated reference mask register the reference mask includes a bit associated with each possible port on the.