C-16 Sun Blade 1500 Service, Diagnostics, and Troubleshooting Manual • December 2004
■ Out-of-order data return for different cache addresses. In-order data return
from single noncacheable port. In-order data return for same cacheable
address. Order determined by address bus order.
■ Out-of-order data return values are according to the address bus order. Data
return implies completion of prior coherency events, by the requestor, which is
a minimal requirement, but also by all other ports, implicitly.
■ Four TransIDs per Device ID
■ Optional dead cycle for bus turnaround
C.4.2 JIO Information
The Sun Blade 1500 workstation uses the JIO I/O bridge as the bridge from the JBus
to the PCI buses. JIO is a companion core-logic ASIC to the UltraSPARC IIIi CPU.
The I/O bridge and UltraSPARC IIIi communicate through JBus. The central task of
I/O bridge is to be the point of access to I/O, and system interrupts.
C.4.2.1 Key Features
The following are key features of the JIO:
■ JBus interface
■ Two 64-bit/66MHz PCI leafs
■ I/O cache (8 x 64-bytes)
■ One per leaf
■ Fully associative
■ In JBus coherency space
■ I/O MMU
■ One per leaf
■ Fully associative TLB
■ Mondo dispatch unit
■ Byte twisting
C.4.2.2 JIO Block Diagram
FIGURE C-5 shows the block diagram for the JIO I/O bridge.
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