In performing memory management, an upgrade client of a host device identifies and reserves memory blocks large enough to accommodate new software components by performing sequential searches of first and second memory areas. The new software components are updated versions of components of original software files. When the new component size exceeds that of available blocks of the first and second memory areas, the upgrade client rewrites the first memory area to eliminate unused memory blocks, reapportions the first and second memory areas, writes the new component to the second memory area, and updates a vector table. To access host device software components, the upgrade client receives a function call from the main program of the host device including identification information of corresponding software files, reads a start address of the corresponding software files from the vector table, and generates a call for the corresponding software files.