HP proprietary bus. Initially used for I/O, but PA-7100LC & PA-7300LC processors connect directly to the GSC bus. GSC comes in several variants: GSC-1X The original GSC bus implemented on PCX-L and used in the Gecko, Mirage and Electra computers. Peak Bandwidth 142MB/s w/DMA, 106 MB/s with PIO writes. GSC+ Enhancements added for KittyHawk/SkyHawk (U2 chip) that allow for pending transactions. GSC+ enhancements are orthogonal to the GSC-1.5X and GSC-2X enhancements. Aka "Extended GSC" or "EGSC". GSC-1.5X GSC-1X with an additional variable length write transaction. GSC-2X GSC-1.5X with a protocol enhancement to allow data to be sent at double the GCLK rate (Peak bandwidth = 256 MB/s)