Filter
Top Products
MULTIBUS
II
AND Intel386 DX MICROPROCESSOR
decoder distinguishes between local, interconnect, and iPSB accesses. PLDs control the
buffering of signals between the Intel386 DX microprocessor, BAC, MIC,
8751
Micro-
controller, and iPSB bus.
10.3 LOCAL BUS EXTENSION (iLBX II)
The iLBX II bus extension
is
a high-speed execution bus designed for quick access to
off-board memory.
One iLBX II bus extension can support either two processing sub-
systems (called the primary requesting agent and the secondary requesting agent) plus
four memory subsystems, or a single processing subsystem plus
five
memory subsystems.
A MULTIBUS II system may contain more than one iLBX II bus extension to meet its
memory requirements.
The iLBX II bus extension features a 26-bit address bus and a separate 32-bit data bus.
Because these paths are separate, the extension allows pipelining of transfer cycles; the
request phase of a transfer cycle can overlap the reply phase of the previous cycle.
Other features of the iLBX II bus extension are:
• A unidirectional handshake for fast data transfers
• Mutual exclusion capability to control multiported memory
• Interconnect space (for each bus agent) through which the primary requesting agent
initializes and configures all other bus agents.
.
10.4 SERIAL SYSTEM BUS (iSSB)
The Serial System Bus (iSSB) provides a simple, low-cost alternative to the Parallel
System Bus
(iPSB) bus. In applications that do not require the high performance of the
iPSB bus, the
iSSB
bus can provide some cost reduction. In systems containing both the
iPSB bus and the
iSSB
bus, the iSSB bus provides an alternate path for interface control,
diagnostics, or redundancy.
The iSSB bus can contain up to 32 bus agents distributed over a maximum of
10
meters.
Bus control
is
determined through an access protocol called Carrier Sense Multiple
Access with Collision Detection
(CSMNCD).
This protocol allows agents to transmit
data whenever they are ready.
In case of simultaneous transmission
by
two
or more bus
agents, the
iSSB
invokes a deterministic collision resolution algorithm to grant fair
access to
all
agents.
From the application point of view, the error detection capability of the
iSSB
bus, cou-
pled with an intelligent bus agent interface (able to retransmit) makes the iSSB bus as
reliable as the
iPSB bus, even though the
iSSB
bus may be up to
10
meters long.
10-7