In a computer system supporting memory compression and wherein data is stored on a disk in a different compressed format, and wherein an IOA (input/output adaptor)/IOP (input/output processor) selectively reads from and writes to a main memory through a direct memory access (DMA) operation, a method for transmitting compressed data from the IOA/IOP to the main memory includes reserving a set of free memory sectors to contain the data in said main memory, sending to the IOA/IOP addresses of said memory sectors, copying the data from the IOA/IOP to said memory sectors using said DMA operation, constructing at the IOA/IOP compressed memory directory information defining how and where the data is stored in memory, sending the memory directory information to a memory controller, and storing the memory directory information in the compressed memory directory structure.