AT91SAM-ICE User Guide
7-3
6206B–ATARM–04-Mar-08
Open collector
A signal that may be actively driven LOW by one or more drivers, and is otherwise passively pulled
HIGH. Also known as a “wired AND” signal.
Processor Core
The part of a microprocessor that reads instructions from memory and executes them, including the
instruction fetch unit, arithmetic and logic unit and the register bank. It excludes optional coprocessors,
caches, and the memory management unit.
Program Status Register (PSR)
Contains some information about the current program and some information about the current proces-
sor. Often, therefore, also referred to as Processor Status Register.
Is also referred to as Current PSR (CPSR), to emphasize the distinction between it and the Saved PSR
(SPSR). The SPSR holds the value the PSR had when the current function was called, and which will be
restored when control is returned.
Remapping
Changing the address of physical memory or devices after the application has started executing. This is
typically done to allow RAM to replace ROM once the initialization has been done.
Remote Debug Interface (RDI)
RDI is an open ARM
®
standard procedural interface between a debugger and the debug agent. The wid-
est possible adoption of this standard is encouraged.
RTCK
Returned TCK. The signal which enables Adaptive Clocking.
RTOS
Real Time Operating System.
Scan Chain
A group of one or more registers from one or more TAP controllers connected between TDI and TDO,
through which test data is shifted.
Semihosting
A mechanism whereby the target communicates I/O requests made in the application code to the host
system, rather than attempting to support the I/O itself.
SWI
Software Interrupt. An instruction that causes the processor to call a programer-specified subroutine.
Used by ARM
®
to handle semihosting.
TAP Controller
Logic on a device which allows access to some or all of that device for test purposes. The circuit func-
tionality is defined in IEEE1149.1.
Target
The actual processor (real silicon or simulated) on which the application program is running.
