80960KB 查看數據表（PDF） - Intel

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80960KB

EMBEDDED 32-BIT MICROPROCESSOR WITH INTEGRATED FLOATING-POINT UNIT

Intel 

80960KB

1.1 Key Performance Features

The 80960 architecture is based on the most recent

advances in microprocessor technology and is

grounded in Intel’s long experience in the design and

manufacture of embedded microprocessors. Many

features contribute to the 80960KB’s exceptional

performance:

1. Large Register Set. Having a large number of

registers reduces the number of times that a

processor needs to access memory. Modern

compilers can take advantage of this feature to

optimize execution speed. For maximum flexi-

bility, the 80960KB provides thirty-two 32-bit

registers and four 80-bit floating point registers.

(See Figure 2.)

2. Fast Instruction Execution. Simple functions

make up the bulk of instructions in most

programs so that execution speed can be

improved by ensuring that these core instruc-

tions are executed as quickly as possible. The

most frequently executed instructions such as

register-register moves, add/subtract, logical

operations and shifts execute in one to two

cycles. (Table 1 contains a list of instructions.)

3. Load/Store Architecture. One way to improve

execution speed is to reduce the number of

times that the processor must access memory

to perform an operation. As with other

processors based on RISC technology, the

80960KB has a Load/Store architecture. As

such, only the LOAD and STORE instructions

reference memory; all other instructions

operate on registers. This type of architecture

simplifies instruction decoding and is used in

combination with other techniques to increase

parallelism.

4. Simple Instruction Formats. All instructions

in the 80960KB are 32 bits long and must be

aligned on word boundaries. This alignment

makes it possible to eliminate the instruction

alignment stage in the pipeline. To simplify the

instruction decoder, there are only five

instruction formats; each instruction uses only

one format. (See Figure 3.)

5. Overlapped Instruction Execution. Load

operations allow execution of subsequent

instructions to continue before the data has

been returned from memory, so that these

instructions can overlap the load. The

80960KB manages this process transparently

to software through the use of a register score-

board. Conditional instructions also make use

of a scoreboard so that subsequent unrelated

instructions may be executed while the condi-

tional instruction is pending.

6. Integer Execution Optimization. When the

result of an arithmetic execution is used as an

operand in a subsequent calculation, the value

is sent immediately to its destination register.

Yet at the same time, the value is put on a

bypass path to the ALU, thereby saving the

time that otherwise would be required to

retrieve the value for the next operation.

7. Bandwidth Optimizations. The 80960KB gets

optimal use of its memory bus bandwidth

because the bus is tuned for use with the

on-chip instruction cache: instruction cache

line size matches the maximum burst size for

instruction fetches. The 80960KB automatically

fetches four words in a burst and stores them

directly in the cache. Due to the size of the

cache and the fact that it is continually filled in

anticipation of needed instructions in the

program flow, the 80960KB is relatively insen-

sitive to memory wait states. The benefit is that

the 80960KB delivers outstanding performance

even with a low cost memory system.

8. Cache Bypass. If a cache miss occurs, the

processor fetches the needed instruction then

sends it on to the instruction decoder at the

same time it updates the cache. Thus, no extra

time is spent to load and read the cache.

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