80960HA/HD/HT

subsystems with minimum system complexity. To reduce the effect of wait states, the bus design is decoupled from the core. This lets the processor execute instructions while the bus performs memory accesses independently.

The Bus Controller’s key features include:

•Demultiplexed, Burst Bus to support most efficient DRAM access modes

•Address Pipelining to reduce memory cost while maintaining performance

•32-, 16- and 8-bit modes to facilitate I/O interfacing

•Full internal wait state generation to reduce system cost

•Little and Big Endian support

•Unaligned Access support implemented in hardware

•Three-deep request queue to decouple the bus from the core

•Independent physical and logical address space characteristics

2.2.3On-Chip Caches and Data RAM

As shown in Figure 1, the 80960Hx provides generous on-chip cache and storage features to decouple CPU execution from the external bus. The processor includes a 16 Kbyte instruction cache, an 8 Kbyte data cache and 2 Kbytes of Data RAM. The caches are organized as 4-way set associative. Stores that hit the data cache are written through to memory. The data cache performs write allocation on cache misses. A fifteen-set stack frame cache allows the processor to rapidly allocate and deallocate local registers. All of the on-chip RAM sustains a 4-word (128-bit) access every clock cycle.

2.2.4Priority Interrupt Controller

The interrupt unit provides the mechanism for the low latency and high throughput interrupt service essential for embedded applications. A priority interrupt controller provides full programmability of 240 interrupt sources with a typical interrupt task switch (latency) time of 17 core clocks. The controller supports 31 priority levels. Interrupts are prioritized and signaled within 10 core clocks of the request. When the interrupt has a higher priority than the processor priority, the context switch to the interrupt routine would typically complete in another seven bus clocks.

External agents post interrupts through the 8-bit external interrupt port. The Interrupt unit also handles the two internal sources from the Timers. Interrupts may be level- or edge-triggered.

2.2.5Guarded Memory Unit

The Guarded Memory Unit (GMU) provides memory protection without the address translation found in Memory Management Units. The GMU contains two memory protection schemes: one prevents illegal memory accesses, the other detects memory access violations. Both signal a fault to the processor. The programmable protection modes are: user read, write or execute; and supervisor read, write or execute.

Datasheet

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Intel 80960HA, 80960HD, 80960HT manual On-Chip Caches and Data RAM
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80960HT, 80960HA, 80960HD specifications

The Intel 80960 family of microprocessors, introduced in the late 1980s, marked a significant evolution in the landscape of embedded systems and high-performance computing. The series included notable members such as the 80960HD, 80960HA, and 80960HT, each offering distinct features, technologies, and characteristics tailored for specific applications.

The Intel 80960HD was primarily designed for high-performance applications, such as real-time processing and advanced embedded control systems. With a robust architecture, the 80960HD featured a 32-bit data bus and a 32-bit address bus, enabling it to access a larger memory space and providing superior performance for computational tasks. It included a sophisticated instruction set that facilitated efficient execution, particularly for computationally intensive tasks. The internal architecture also supported pipelining, allowing multiple instructions to be processed simultaneously, thus enhancing throughput.

The 80960HA variant was tailored for high-availability applications, making it ideal for embedded systems where reliability is paramount. This model incorporated features that emphasized fault tolerance and stability, ensuring that systems relying on it could maintain operational integrity even in the event of component failures. The 80960HA showcased enhanced error detection and correction capabilities, which contributed to its reputation as a dependable choice for mission-critical applications.

On the other hand, the 80960HT was designed to meet the needs of high-performance telecommunications and networking applications. Recognized for its ability to handle multiple tasks concurrently, the 80960HT included advanced features such as built-in support for multitasking and real-time processing. This made it an excellent fit for applications that demanded rapid data handling and processing, such as routers and switches in networking environments. Its architecture allowed for efficient context switching, ensuring that multiple processes could execute seamlessly.

All three variants utilized the same family architecture, enabling easy integration and compatibility across different applications. They also supported various memory management techniques, such as virtual memory and caching, enhancing their performance in diverse operating conditions. With their combination of high processing power, reliability, and flexibility, the Intel 80960 family of microprocessors played a crucial role in advancing embedded computing technologies, paving the way for modern-day processors and systems. The 80960 series remains a noteworthy chapter in the evolution of microprocessor design, reflecting the growing demands of the computing landscape during its time.
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