Test register

Test register

Test register was a register used by the processor, usually to do a self-test. Most of these registers were undocumented, and used by specialized software. In the x86 series, these registers were marked TR4 to TR7. Usually, regular programs don't require these registers to work. In the newer CPU sets, the test registers are removed.

Two test registers, TR6 and TR7, were provided for the purpose of testing. TR6 was the test command register, and TR7 was the test data register. These registers were accessed by variants of the MOV instruction. A test register may either be the source operand or the destination operand. The MOV instructions are defined in both real-address mode and protected mode. The test registers are privileged resources. In protected mode, the MOV instructions that access them can only be executed at privilege level 0. An attempt to read or write the test registers when executing at any other privilege level causes a general protection exception.

ee also

*Control register
*Debug register


Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Test and tagging — is a generic name given to the process of visually inspecting and electrically testing in service electrical equipment for personal use and/or safety. Colloquially, it is also referred to as; tagging, test tag, test and tag, electrical tagging,… …   Wikipedia

  • Test-and-set — Test and set  простая неразрывная (атомарная) процессорная инструкция, которая копирует значение переменной в регистр, и устанавливает некое новое значение. Во время исполнения данной инструкции процессор не может прервать её выполнение и… …   Википедия

  • register of eligibles — A list of applicants for vacancies in an installation. The list is usually arranged by descending test scores …   Glossary of postal terms

  • Register machine — In mathematical logic and theoretical computer science a register machine is a generic class of abstract machines used in a manner similar to a Turing machine. All the models are Turing equivalent. Contents 1 Overview 2 Formal definition 3 …   Wikipedia

  • Test-and-set — In computer science, the test and set instruction is an instruction used to both test and (conditionally) write to a memory location as part of a single atomic (i.e. non interruptible) operation. This means setting a value, but first performing… …   Wikipedia

  • Test light — Neon test lamp for line voltages A test light, test lamp, voltage tester, or mains tester is a very simple piece of electronic test equipment used to determine the presence or absence of an electric voltage in a piece of equipment under test.… …   Wikipedia

  • Register transfer language — In computer science, register transfer language (RTL) is a term used to describe a kind of intermediate representation (IR) that is very close to assembly language, such as that which is used in a compiler. Academic papers and textbooks also… …   Wikipedia

  • TEST (x86 instruction) — In the x86 assembly language, the TEST instruction performs a bitwise AND on two operands. The flags SF, ZF, PF, CF, OF and AF are modified while the result of the AND is discarded. There are 9 different opcodes for the TEST instruction depending …   Wikipedia

  • Test skill — Testskill is a game devoted to trying to correctly predict performances by individual cricket players in international cricket matches, where the best 4 performers from each team are selected by the tipster, and points are awarded depending on… …   Wikipedia

  • Control register — A control register is a processor register which changes or controls the general behavior of a CPU or other digital device. Common tasks performed by control registers include interrupt control, switching the addressing mode, paging control, and… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”