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In term of CPU action, data transfer operations are perhaps the simplest type. If both source and destination are registers, then the CPU simply causes data to be transferred from one register to another; this is an operation internal to the CPU. If one or both operands are in memory, then (he CPU must perform some or all of following actions:

1. Calculate the memory address, based on the address mode

2. If the address refers to virtual memory, translate from virtual to actual mem­ory address.

3. Determine whether the addressed item is in cache.

4. If not, issue a command lo the memory module.


Operation mnemonic Name Number of bits transferred Description
L Load 32 Transfer from memory in register
LH Load half-word 16 Transler from memory to register
ST Store 32 Transfer from register to memory
STH Store half-word 16 Transfer from register to memory

3.2 arithmetic

Most machines provide the basic arithmetic operations of add, subtract, multiply, and divide. These are invariably provided for signed integer (fixed-point) numbers, Often they are also provided for floating-point and packed decimal numbers.

Other possible operations include a variety of single-operand instructions: for example.

• Absolute: Take the absolute value of the operand.

• Negate: Negate the Operand.

• Increment.: Add 1 to the operand.

• Decrement: Subtract 1 from the operand

3.3 logical

Most machines also provide a variety of operations for manipulating individual bits of a word or other addressable units, often referred to as "bit twiddling." They are based upon Boolean operations.

Some of the basic logical operations that can be performed on Boolean or binary data are AND, OR, NOT, XOR, …

These logical operations can be applied bitwise to n-bit logical data units. Thus, if two registers contain the data

(R1) - 10100101 (R2) - 00001111


(R1) AND (R2) – 00000101

In addition lo bitwise logical operations, most machines provide a variety of shifting and rotating functions such as shift left, shift right, right rotate, left rotate…

3.4 conversion

Conversion instructions are those that change the format or operate on the format of data. An example is converting from decimal to binary.

3.5 input/output

As we saw, there are a variety of approaches taken, including isolated programmed IO, memory-mapped programmed I/O, DMA, and the use of an I/O processor. Many implementations provide only a few I/O instructions, with the specific actions spec­ified by parameters, codes, or command words.

3.6 system controls

System control instructions are those that can he executed only while the proces­sor is in a certain privileged state or is executing a program in a special privileged area of memory, typically, these instructions are reserved for the use of the oper­ating system.

Some examples of system control operations are as follows. A system control instruction may read or alter a control register. Another example is an instruction to read or modify a storage protection key, such us is used in the S/390 memory system. Another example is access to process control blocks in a multiprogramming system.

Questions & Answers

anyone know any internet site where one can find nanotechnology papers?
Damian Reply
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Computer architecture. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10761/1.1
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