DESCRIPTION
The QED RM5271 is a highly integrated superscalar micro-
processor that is ideally suited for high-end embedded con-
trol applications such as internetworking, high-performance
image manipulation, high-speed printing, and 3-D visual-
ization.The RM5271 is also applicable to the low end work-
station market where its balanced integer and floating-point
performance and direct support for a large secondary
cache (up to 2MB) provide outstanding price/performance
combination with its high-throughput fully pipelined floating-
point execution unit, the superscalar capability of the
RM5271 provides unparalleled price/performance in com-
putationally intensive embedded applications.
CPU Registers
The RM5271 CPU contains 32 general purpose registers,
two special purpose registers for integer multiplication and
division, a program counter, and no condition code bits.
Figure 1 shows the user visible state.
HARDWARE OVERVIEW
Pipeline
The RM5271 offers a high-level of integration targeted at
high-performance embedded applications. The key ele-
ments of the RM5271 are briefly described below.
For integer operations, loads, stores, and other non-float-
ing-point operations, the RM5271 uses a 5-stage pipeline.
In addition to the 5-stage integer pipeline, the RM5271
uses an extended 7-stage pipeline for floating-point opera-
tions.
Superscalar Dispatch
The RM5271 has an asymmetric superscalar dispatch unit
which allows it to issue an integer instruction and a floating-
point computation instruction simultaneously. With respect
to superscalar issue, integer instructions include alu,
branch, load/store, and floating-point load/store, while float-
ing-point computation instructions include floating-point
add, subtract, combined multiply-add, converts, etc. In
Figure 2 shows the RM5271 integer pipeline. Up to five
integer instructions can be executing simultaneously.
General Purpose Registers
63
0
0
Multiply/Divide Registers
63
HI
0
0
r1
r2
•
63
LO
•
•
Program Counter
•
63
0
r29
r30
r31
PC
Figure 1 CPU Registers
2
RM5271 Microprocessor, Document Rev. 1.3
Quantum Effect Devices
www.qedinc.com
ETC [ ETC ]
