GIO(4) | Device Drivers Manual (sgi) | GIO(4) |
gio
— Graphics I/O
GIO bus
gio0 at imc0
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:
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.
April 18, 2012 | OpenBSD-current |