Texas Instruments TMS380C26 specifications Description

TMS380C26

NETWORK COMMPROCESSOR

SPWS010A±APRIL 1992±REVISED MARCH 1993

description

The TMS380C26 is a single-chip network communications processor (commprocessor) that supports token ring, or Ethernet Local Area Networks (LANs). Either token ring at data rates of 16 Mbps or 4 Mbps, or Ethernet at a data rate of 10 Mbps, can be selected. A flexible configuration scheme allows network type and speed to be configured by hardware or software. This allows the design of LAN subsystems which support both token ring and Ethernet networks, by electrically or physically switched network front-end circuits.

The TMS380C26 conforms to IEEE 802.5±1989 standards and has been verified to be completely IBM Token-Ring compatible. By integrating the essential control building blocks needed on a LAN subsystem card into one device, the TMS380C26 can ensure that this IBM compatability is maintained in silicon.

The TMS380C26 conforms to ISO/IEC 8802±3 (ANSI/IEEE Std 802.3) CSMA/CD standards, and the Ethernet ºBlue Bookº standard.

The high degree of integration of the TMS380C26 makes it a virtual LAN subsystem on a single chip. Protocol handling, host system interfacing, memory interfacing, and communications processing are all provided through the TMS380C26. To complete LAN subsystem design, only the network interface hardware, local memory, and minimal additional components such as PALs and crystal oscillators need to be added.

The TMS380C26 provides a 32-bit system memory address reach with a high-speed bus-master DMA interface that supports rapid communications with the host system. In addition, the TMS380C26 supports direct I/O and a low-cost 8-bit pseudo-DMA interface that requires only a chip select to work directly on an 80x8x 8-bit slave I/O interface. Finally, selectable 80x8x or 68xxx-type host system bus and memory organization add to design flexibility.

The TMS380C26 supports addressing for up to two Megabytes of local memory. This expanded memory capacity can improve LAN subsystem performance by minimizing the frequency of host LAN subsystem communications by allowing larger blocks of information to be transferred at one time. The support of large local memory is important in applications that require large data transfers (such as graphics or data base transfers) and in heavily loaded networks where the extra memory can provide data buffers to store data until it can be processed by the host.

The proprietary CPU used in the TMS380C26 allows protocol software to be downloaded into RAM or stored in ROM in the local memory space. By moving protocols (such as LLC) to the LAN subsystem, overall system performance is increased. This is accomplished due to the the offloading of processing from the host system to the TMS380C26, which may also reduce LAN subsystem-to-host communications. As other protocol software is developed, greater differentiation of end products with enhanced system performance will be possible.

In addition, the TMS380C26 includes hardware counters that provide realtime error detection and automatic frame buffer management. These counters control system bus retries, burst size, and track host and LAN subsystem buffer status. Previously, these counters needed to be maintained in software. By integrating them into hardware, software overhead is removed and LAN subsystem performance is improved.

The TMS380C26 implements a TI-patented Enhanced Address Copy Option (EACO) interface. This interface supports external address checking devices, such as the TMS380SRA Source Routing Accelerator. The TMS380C26 has a 128-word external I/O space in its memory map to support external address-checker devices and other hardware extensions to the TMS380 architecture. Hardware designed in conformance with TI's Specification for External Adapter-bus Devices (SEADs) can map registers into this external I/O space and post interrupts to the TMS380C26.

The major blocks of the TMS380C26 include the Communications Processor (CP), System Interface (SIF), Memory Interface (MIF), Protocol Handler (PH), Clock Generator (CG), and the Adapter Support Function (ASF) as shown in Figure 2.

The TMS380C26 is available in a 132-pin JEDEC plastic quad flat pack and is rated from 0°C to 70°C.

IBM is a registered trademark of International Business Machines Corporation.

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