GIO(4)              NetBSD/sgimips Kernel Interfaces Manual             GIO(4)

NAME
     gio -- SGI's Graphics I/O (GIO) bus (an early PCI-like bus)

SYNOPSIS
     gio0 at imc0
     gio0 at pic0

DESCRIPTION
     The gio bus is a bus for connecting high-speed peripherals to the main
     memory and CPU.  The devices themselves are typically (but not necessar-
     ily) connected to the hpc(4) peripheral controller, and memory and CPU
     are accessed through the imc(4) (Indy Memory Controller) or pic(4) (Pro-
     cessor Interface Controller).  The gio bus is found on the Personal Iris
     4D/3x, Indigo, Indy, Challenge S, Challenge M, and Indigo2 machines and
     exists in three incarnations: GIO32, GIO32-bis, and GIO64.

SEE ALSO
     giopci(4), grtwo(4), hpc(4), imc(4), light(4), newport(4), pic(4)

HISTORY
     The gio driver first appeared in NetBSD 1.5.

CAVEATS
     Challenge S systems may use only one gio DMA-capable expansion card,
     despite having two slots.  Cards based on the hpc(4) controller, such as
     the GIO32 scsi and E++ Ethernet adapters, must be placed in slot 1 (clos-
     est to the side of the case).  All other cards must be placed in slot 0
     (adjacent to the memory banks).

     Indigo2 and Challenge M systems contain either three or four GIO64 con-
     nectors, depending on the model.  However, in both cases only two elec-
     trically distinct slots are present.  Therefore, distinct expansion cards
     may not share physical connectors associated with the same slot.  Refer
     to the PCB stencils to determine the association between physical connec-
     tors and slots.

BUGS
     Systems employing the imc(4) may experience spurious SysAD bus parity
     errors when using expansion cards, which do not drive all data lines dur-
     ing a CPU PIO read.  The only workaround is to disable SysAD parity
     checking when using such cards.

NetBSD 5.0_STABLE              December 25, 2006             NetBSD 5.0_STABLE
