NAME
gio —
Graphics I/O GIO bus
SYNOPSIS
gio0 at imc0
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 necessarily) connected to the
hpc(4) peripheral controller, and memory and CPU are accessed through
the imc(4) system controller. The gio bus is
found on the Indigo, Indy, Challenge S, Challenge M, and Indigo2 machines
and exists in three incarnations: GIO32, GIO32-bis, and GIO64.
The devices currently supported under OpenBSD are:
- grtwo(4)
- SGI Express graphics
- hpc(4)
- SGI High performance Peripheral Controller
- impact(4)
- SGI Impact (aka Mardigras) graphics
- light(4)
- SGI Light graphics
- newport(4)
- SGI Newport graphics
SEE ALSO
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 (closest 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
connectors, depending on the model. However, in both cases only two
electrically distinct slots are present. Therefore, distinct expansion cards
may not share physical connectors associated with the same slot. On the
other hand, these apparently redundant slot connectors allow multiple board
assemblies to draw more power from the bus, and also helps mix
gio and EISA boards in the same chassis. In all
systems, the upper two GIO64 connectors are GIO slot 1, while the lower
connectors (either one or two of them) are GIO slot 0.