Intel 80960KB User Manual

80960KB
6
Figure 4. Multiple Register Sets Are Stored On-Chip
REGISTER
CACHE
ONE OF FOUR
LOCAL
REGISTER SETS
LOCAL REGISTER SET
R
15
R
0
31
0
1.1.7 Floating-Point Arithmetic
In the 80960KB, floating-point arithmetic has been
made an integral part of the architecture. Having the
floating-point unit integrated on-chip provides two
advantages. First, it improves the performance of the
chip for floating-point applications, since no
additional bus overhead is associated with
floating-point calculations, thereby leaving more time
for other bus operations such as I/O. Second, the
cost of using floating-point operations is reduced
because a separate coprocessor chip is not
required.
The 80960KB floating-point (real-number) data types
include single-precision (32-bit), double-precision
(64-bit) and extended precision (80-bit) floating-point
numbers. Any registers may be used to execute
floating-point operations.
The processor provides hardware support for both
mandatory and recommended portions of IEEE
Standard 754 for floating-point arithmetic, including
all arithmetic, exponential, logarithmic and other
transcendental functions. Table 3 shows execution
times for some representative instructions.
1.1.8 High Bandwidth Local Bus
The 80960KB CPU resides on a high-bandwidth
address/data bus known as the local bus (L-Bus).
The L-Bus provides a direct communication path
between the processor and the memory and I/O
subsystem interfaces. The processor uses the L-Bus
to fetch instructions, manipulate memory and
respond to interrupts. L-Bus features include:
• 32-bit multiplexed address/data path
• Four-word burst capability which allows transfers
from 1 to 16 bytes at a time
• High bandwidth reads and writes with
66.7 MBytes/s burst (at 25 MHz)
Table 4 defines L-bus signal names and functions;
Table 5 defines other component-support signals
such as interrupt lines.
Table 3. Sample Floating-Point Execution Times
(µs) at 25 MHz
Function 32-Bit 64-Bit
Add 0.4 0.5
Subtract 0.4 0.5
Multiply 0.7 1.3
Divide 1.3 2.9
Square Root 3.7 3.9
Arctangent 10.1 13.1
Exponent 11.3 12.5
Sine 15.2 16.6
Cosine 15.2 16.6

Intel 80960KB Specifications

General

Brand	Intel
Model	80960KB
Category	Computer Hardware
Language	English