TMS380SRA Datasheet, PDF (2/11 Pages) Texas Instruments – SOURCE-ROUTING ACCELERATOR

TMS380SRA
SOURCEĆROUTING ACCELERATOR
ą
SPWS006 − NOVEMBER 1991
description
The TMS380SRA source-routing accelerator (SRA) device provides the hardware for direct recognition and
parsing of the source-routing field in a token-ring frame. The TMS380SRA is designed to interface directly to
the TMS380Cx6. The TMS380SRA searches the received frame for frames that need to be forwarded to the
adjacent ring by examining the source-routing field. If a frame is to be forwarded, the frame is copied by the
adapter and transferred to the attached system through the system interface of the TMS380Cx6. A second
adapter with the TMS380SRA can also be included in the attached system (thus forming a bridge) to provide
an identical function for the second ring. Transfer of data between the two rings (bridging) occurs under attached
system-software control.
A block diagram of the TMS380SRA is shown in Figure 1. The internal registers fall into two categories: registers
that can be set by the host software for the specific bridge parameters for this adapter, and dynamic registers
that are loaded with the received frames-routing information as read from the adapter bus transfer. The routing
information is compared to the specified bridge parameters, which determines the value to be placed on the
XMATCH and XFAIL pins. The memory-interface (MIF) address output during memory cycles is shown in
Table 1. Status information is provided on the MADH0 −MADH7 signals in the second quarter of the memory
cycle (shaded area). MADH6 and MADH7 are the bits that can be used by an EACO device. The information
provided in these bits during the second quarter of the memory cycle can be decoded as follows:
MADH6
MADH7
H=
L=
H=
L=
The TMS380Cx6 PH RX DMA machine is transferring a word of received
frame data to memory.
At all other times
The TMS380Cx6s PH RX DMA machine is transferring the first word of a
new received frame to memory. In a token-ring frame, the first word contains
the AC and FC fields.
At all other times
The decode of the rest of the status information is shown in Table 2 and Table 3.
The TMS380SRA is available in a 44-lead plastic chip-carrier package (FN suffix) and is characterized for
operation from 0°C to 70°C (L suffix). The electrostatic-discharge protection of the TMS380SRA is rated at
500 V human-body model (HBM).
MBCLK1
MBCLK2
MRESET
MDDIR
MBEN
MAXPH
MAXPL
MADH(0 − 7) ¹⁸
MADL(0 − 7)
2
VCC
GND
4
Control
Registers
Containing:
SET.BRIDGE.PARMS
Command Parameters
− Source Ring
− Target Ring
− Bridge Number
− Options
Dynamic Storage
− Bus Status Byte
− Routing-Information
Field Data
Compare
XMATCH
XFAIL
State
Machine
Frame
Start
Control
Figure 1. TMS380SRA Block Diagram
XMATCH
XFAIL
2
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265
• POST OFFICE BOX 1443 HOUSTON, TEXAS 77251−1443