Specifications

Computer Architecture and Maintenance (G-Scheme-2014)
• AGP doesn't share bandwidth with other devices, whereas the PCI bus does
share bandwidth.
AGP PCI
1 Pipelined Requests Non-pipelined
2 Address/Data de-multiplexed Address/Data multiplexed
3 Peak at 533 MB/s in32 bits Peak at 133 MB/s in 32 bits
4 Single target, single master Multi target, multi master
5
Memory read/write only
No other input/output operations
Link to entire system
6 High/low priority queues No priority queues
Q. What does all this mean?
DIME short for Direct Memory Execute, DIME allows for video card to use
some of the main memory for texture memory with 3D graphics.
Usually video cards have 4 MB of RAM, some have 8 MB of RAM, but
DIME allows for 12, 16, or even more memory to be used by allocating
some of the main system memory.
Pipelining As you should know from reading Hennessy and Patterson's 'great'
Computer Architecture book, pipelining is an implementation
technique whereby multiple instructions are overlapped in execution.
A pipeline is just like an assembly line. There are various different steps
(pipe stage or pipe segments) that contribute to the end result. Each of
these steps are done in parallel. The opposite of a pipelined architecture
is a sequential architecture, in which steps are completed sequentially or
one after another, not in parallel.
Sideband
addressing
the AGP bus uses sideband signals to send addressing information
separately from data. This technique allows addresss informaton to be
presented to the bus concurrent with a data transaction. The result is a
more efficient use of the AGP bus for data transfers. With sideband
addressing, AGP utilized 8 extra "sideband lines" which allow the
graphics controller to issue new addresses and requests
simulataneously while data continues to move from previous requests
on the main 32 data/address wires.
Bandwidth the amount of data a network can transport in a certain period of time -
it is the capacity for the rate of transfer, which is usually expressed in
bits per second.
Prepared By – Prof. Manoj.kavedia (9860174297 – 9324258878 ) (www.kavediasir.yolasite.com)
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