Description
Like most busses of the era, GIO was a 32-bit address and data multiplexed bus that was normally clocked at 25 or 33 MHz. This meant that the bus uses the same path for addressing and data, thus normally requiring three cycles to transfer a single 32-bit value; one cycle to send the address, the next to send the data and then another to read or write it. This limited the bus to a maximum throughput of about 16 Mbyte/s at 33 MHz for these sorts of small transfers. However the system also included a long-burst read/write mode that allowed continual transfers of up to 4 kilobytes of data (the fundamental page size in R3000-based SGI machines); using this mode dramatically increased the throughput to 132 Mbyte/s (32 bits per cycle * 33 MHz). GIO also included a "real time" interrupt allowing devices to interrupt these long transfers if needed. Bus arbitration was controlled by the Processor Interface Controller (PIC) in the original R3000-based SGI Indigo systems.
Physically, GIO used a 96-pin connector and fairly small cards 6.44 inches (16.3576 cm) long by 3.375 inches (8.5725 cm) wide. In the Indigo series the cards were aligned vertically above each other within the case, as opposed to the more common arrangement where the cards lie at right angles to the motherboard. This led to a "tall and skinny" case design. Since the cards were "above" each other in-line, it was possible to build a card that connected to both connectors on the computer's motherboard, thereby offering more room.
Read more about this topic: Gio
Famous quotes containing the word description:
“The great object in life is Sensation—to feel that we exist, even though in pain; it is this “craving void” which drives us to gaming, to battle, to travel, to intemperate but keenly felt pursuits of every description whose principal attraction is the agitation inseparable from their accomplishment.”
—George Gordon Noel Byron (1788–1824)
“An intentional object is given by a word or a phrase which gives a description under which.”
—Gertrude Elizabeth Margaret Anscombe (b. 1919)
“I was here first introduced to Joe.... He was a good-looking Indian, twenty-four years old, apparently of unmixed blood, short and stout, with a broad face and reddish complexion, and eyes, methinks, narrower and more turned up at the outer corners than ours, answering to the description of his race. Besides his underclothing, he wore a red flannel shirt, woolen pants, and a black Kossuth hat, the ordinary dress of the lumberman, and, to a considerable extent, of the Penobscot Indian.”
—Henry David Thoreau (1817–1862)