AMD-762 Advanced Micro Devices, AMD-762 Datasheet - Page 19

• Manufacturer Part Number: AMD-762
• Description: System Controller
• Manufacturer: Advanced Micro Devices

24416C—December 2001
2
2.1
2.1.1
Chapter 2
Functional Operation
Processor Interface
Out of Order, Split Transaction
Th is s e c t i o n d e s cr i b e s t h e f u n c t i o n a l o p e r a t i on o f t h e
AMD-762™ system controller.
Th e two AMD At h l o n p roce s sor syst e m b u s e s a r e hig h -
p e r for ma n c e, out-of-ord e r, sp lit -tr a nsa c t ion buses, each
capable of transferring one processor command and one probe
response, one chip-set response and one probe request, and one
data packet simultaneously. Data and command packets are
transferred as packets of two, four, or eight datums on each
edge of the 100-MHz or 133-MHz clock.
Th e split t r a n sa ct ion buses sep a r a t e t h e t ra n s f e r of the
command and the associated data into different transactions
on different buses. Data may be returned in a different order
than it was requested, subject to ordering rules.
A read transaction consists of a Read command sent from the
processor to the memory system over the SADDOUT bus. When
t h e m e mory system is re a dy to re t u r n d a t a , a R e a d Da t a
command is sent to the processor over the SADDIN bus to alert
the processor that data is coming and identify the associated
data request. The data is sent to the processor over the SDATA
bus a programmable number of clocks later. Similarly, a write
transaction is sent to the chipset over the SADDOUT bus, the
chipset requests the associated write data over the SADDIN
b u s , a n d t h e d a t a i s t ra n s f e r r e d ove r t h e S DATA b u s a
p rogra mmable nu m b er of clocks lat e r. Pr obes a n d p rob e
responses are piggybacked wit h the other commands on the
SADDIN and SADDOUT bus.
Th e split t r a n s a ct ion sch e m e p rovides a h i g h d e g re e of
parallelism between the various buses and facilitates pipeline
flow or memory requests and responses.
Preliminary Information
Functional Operation
AMD-762™ System Controller Data Sheet
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