GSC bus


GSC is a bus used in many of the HP 9000 workstations and servers. The acronym has various explanations, including Gecko System Connect, Gonzo System Connect and General System Connect.
GSC was a general 32-bit I/O bus, similar to NuBus or Sun's SBus, although it was also used as a processor bus with the PA-7100LC and PA-7300LC processors. Several variations were produced over time, the later ones running at 40 MHz:
;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+, a.k.a. "Extended GSC" or "EGSC": Enhancements added for KittyHawk/SkyHawk that allow for pending transactions. GSC+ enhancements are orthogonal to the GSC-1.5X and GSC-2X enhancements.
;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, with a peak bandwidth of 256 MB/s.
;HSC: High Speed Connect.
Four types of GSC cards were produced: the GIO cards fit into the larger of the two IO card sockets in the 712 workstation. Several were produced, including a second RS-232 serial port, a serial/10BaseT combo, a second graphics card and a Token Ring card.
The 715/Mirage, 725, 735, 755, B-, C-, and J-class workstations, and the D- and R-class servers, used the so-called "EISA form factor". Many different types of card were produced, including Gigabit Ethernet, single and dual 100Mbit Ethernet, Ultra-2 SCSI, ATM and graphics.
The K- and T-class servers both used the "3x5" form factor, although the different brackets prevent the cards being interchangeable. Fibre channel and Gigabit Ethernet cards both exist.