A computer system utilizes subsystem supplemental memory resources to implement operating system supplemental disk caching. A main system processor (e.g., a central processing unit) processes information associated with main system functions. A bulk memory (e.g., a hard disk) stores the information. A main system memory (e.g., a main RAM) caches portions of the bulk information. A subsystem supplemental memory (e.g., a graphics subsystem RAM) provides storage capacity for subsystem operations (e.g., graphics operations) and supplemental storage for portions of said bulk information associated with main system functions (e.g., functions performed by the main system processor). Information (e.g., main system information) cached in the subsystem supplemental memory can be accessed by the main system processor directly.