80960HA datasheet(9/102 Pages) INTEL

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80960HA/HD/HT

Advance Information Datasheet

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

2.2.3

On-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.

2.2.4

Priority 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. If the interrupt has a higher priority than the processor priority, the

context switch to the interrupt routine would typically complete in another 7 bus clocks.

External agents post interrupts via the 8-bit external interrupt port. The Interrupt unit also handles

the two internal sources from the Timers. Interrupts can be level- or edge-triggered.

2.2.5

Guarded 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.

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