ACT5270
64-Bit Superscaler Microprocessor
Features
s
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Full militarized QED RM5270 microprocessor
Dual Issue superscalar microprocessor - can issue one
integer and one floating-point instruction per cycle
150, 200 MHz operating frequencies – Consult Factory for
latest speeds
q
260 Dhrystone2.1 MIPS
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SPECInt95 5.0, SPECfp95 5.3
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133,
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Integrated secondary cache controller (R5000 compatible)
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Supports
512K or 2MByte block write-through secondary
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High-performance floating point unit
cycle repeat rate for common single precision operations
and some double precision operations
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Two cycle repeat rate for double precision multiply and double
precision combined multiply-add operations
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Single cycle repeat rate for single precision combined multiply-
add operation
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Single
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High performance system interface compatible with RM5260,
R4600, R4700 and R5000
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64-bit
multiplexed system address/data bus for optimum price/
performance with up to 100 MHz operating frequency
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High performance write protocols maximize uncached write
bandwidth
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Supports clock divisors (2, 3, 4, 5, 6, 7, 8)
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5V compatible I/O’s
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IEEE 1149.1 JTAG boundary scan
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MIPS IV instruction set
point multiply-add instruction increases performance in
signal processing and graphics applications
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Conditional moves to reduce branch frequency
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Index address modes (register + register)
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Floating
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Embedded application enhancements
DSP integer Multiply-Accumulate instruction and 3
operand multiply instruction
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I and D cache locking by set
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Optional dedicated exception vector for interrupts
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Specialized
Integrated on-chip caches
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16KB
instruction - 2 way set associative
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16KB data - 2 way set associative
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Virtually indexed, physically tagged
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Write-back and write-through on per page basis
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Pipeline restart on first double for data cache misses
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Fully static CMOS design with power down logic
reduced power mode with WAIT instruction
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6 Watts typical at 3.3V 200 MHz
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Standby
Integrated memory management unit
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Fully
associative joint TLB (shared by I and D translations)
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48 dual entries map 96 pages
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Variable page size (4KB to 16MB in 4x increments)
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208-lead CQFP, cavity-up package (F17)
208-lead CQFP, inverted footprint (F24), Intended to duplicate
the commercial QED footprint
179-pin PGA package (Future
Product)
(P10)
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BLOCK DIAGRAM
Preliminary
eroflex Circuit Technology – RISC TurboEngines For The Future © SCD5270 REV 1 12/22/98
DESCRIPTION
The ACT5270 is a highly integrated superscalar
microprocessor that implements a superset of the
MIPS IV Instruction Set Architecture(ISA). It has a
high performance 64-bit integer unit, a high
throughput, fully pipelined 64-bit floating point unit,
an operating system friendly memory management
unit with a 48-entry fully associative TLB, a 16
KByte 2-way set associative instruction cache, a 16
KByte 2-way set associative data cache, and a
high-performance 64-bit system interface with
support for an optional external secondary cache.
The ACT5270 can issue both an integer and a
floating point instruction in the same cycle.
The ACT5270 is ideally suited for high-end
emb edded
control
applications
such
as
internetworking,
high
performance
image
manipulation, high speed printing, and 3-D
visualization.The ACT5270 is also applicable to the
low end workstation market where its balanced
integer and floating-point performance and direct
support for a large secondary cache (up to 2MB)
provide outstanding price/performance
floating-point operations. Like the R5000, the
ACT5270 does virtual to physical translation in
parallel with cache access.
Integer Unit
As part of the ACT52xx family, the ACT5270
implements the MIPS IV Instruction Set
Architecture, and is therefore fully upward
compatible with applications that run on processors
implementing the earlier generation MIPS I-III
instruction sets. Additionally, the ACT5270 includes
two implementation specific instructions not found
in the baseline MIPS IV ISA but that are useful in
the embedded market place. Described in detail in
the QED RM5270 datasheet, these instructions are
integer multiply-accumulate and 3-operand integer
multiply.
The ACT5270 integer unit includes thirty-two
general purpose 64-bit registers, a load/store
architecture with single cycle ALU operations (add,
sub, logical, shift) and an autonomous multiply/
divide unit. Additional register resources include:
the HI/LO result registers for the two-operand
integer multiply/divide operations, and the program
counter(PC).
HARDWARE OVERVIEW
The ACT5270 offers a high-level of integration
targeted
at
high-performance
embedded
applications. The key elements of the ACT5270 are
briefly described below.
Register File
The ACT5270 has thirty-two general purpose
registers with register location 0 hard wired to zero.
These registers are used for scalar integer
operations and address calculation. The register
file has two read ports and one write port and is fully
bypassed to minimize operation latency in the
pipeline.
Superscalar Dispatch
The ACT5270 has an efficient 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 floating-point computation instructions
include floating-point add, subtract, combined
multiply-add, converts, etc. In combination with its
high throughput fully pipelined floating-point
execution unit, the superscalar capability of the
ACT5270 provides unparalleled price/performance
in
computationally
intensive
embedded
applications.
ALU
The ACT5270 ALU consists of the integer adder/
subtractor, the logic unit, and the shifter. The adder
performs address calculations in addition to
arithmetic operations, the logic unit performs all
logical and zero shift data moves, and the shifter
performs shifts and store alignment operations.
Each of these units is optimized to perform all
operations in a single processor cycle.
CPU Registers
Like all MIPS ISA processors, the ACT5270 CPU
has a simple, clean user visible state consisting of
32 general purpose registers, two special purpose
registers for integer multiplication and division, a
program counter, and no condition code bits.
For additional Detail Information regarding the
operation of the Quantum Effect Design (QED)
RISCMark™ ACT5270™, 64-Bit Superscalar
Microprocessor see the latest QED datasheet
(Revision 1.1 July 1998).
Pipeline
For integer operations, loads, stores, and other
non-floating-point operations, the ACT5270 uses
the simple 5-stage pipeline also found in the
ACT52xx family, R4600, R4700, and R5000. In
addition to this standard pipeline, the ACT5270
uses an extended seven stage pipeline for
Aeroflex Circuit Technology
2
SCD5270 REV 1 12/22/98 Plainview NY (516) 694-6700
ARM Technology
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