
1-2
Introduction
August 2001 - Rev. A
Copyright 2000 by LSI Logic Corporation. All rights reserved.
The ARM memory interface has been designed to allow the performance
potential to be realized without incurring high costs in the memory
system. Speed critical control signals are pipelined to allow system
control functions to be implemented in standard low-power logic, and
these control signals facilitate the exploitation of the fast local access
modes offered by industry standard dynamic RAMs.
1.1.2 LSI Logic’s ARM7TDMI-S Implementation
The ARM7TDMI-S Microprocessor Core described in this manual is LSI
Logic Corporation's proprietary implementation of the ARM7TDMI-S
microprocessor. LSI Logic has optimized this synthesizable version to
facilitate implementation of complex system-on-a-chip ASICs in LSI
Logic's state-of-the-art ASIC flows.
The LSI Logic implementation of the ARM7TDMI-S core is fully hardware
and software compatible with the ARM7TDMI-S core. To implement full
scan, LSI Logic has added four additional test signals to the core (for a
full description of these signals, see
Chapter 2
, “
Signal Descriptions”).
1.2 ARM7TDMI-S Architecture
The ARM7TDMI-S processor has two instruction sets:
the 32-bit ARM instruction set
the 16-bit Thumb
instruction set
The ARM7TDMI-S core is an implementation of the ARMv4T
architecture. For full details on both the ARM and Thumb instruction sets,
refer to the ARM Architecture Reference Manual
1.2.1 Instruction Compression
A typical 32-bit instruction set can manipulate 32-bit integers with single
instructions, and address a large address space much more efficiently
than a 16-bit architecture. When processing 32-bit data, a 16-bit
architecture takes at least two instructions to perform the same task as
a single 32-bit instruction.
When a 16-bit architecture has only 16-bit instructions and a 32-bit
architecture has only 32-bit instructions, overall the 16-bit architecture