HP-PB I/O slot expansion is available beyond the chassis for the HP 3000 99x and 9x9KS Servers and HP 9000 T- and K-Class Enterprise Servers through the addition of a 14-slot HP-PB I/O card cage. Larger database disk storage capacities, additional tape devices for disk storage backup, and added high-speed networking links for processor-to-processor communications and the attachment of networked peripherals, workstations, and PCs can drive the need for additional HP-PB I/O slots. Incremental addition of HP-PB I/O slots allows for cost-effective I/O expansion while providing investment protection for existing HP 3000 or HP 9000 Enterprise Servers.