What is Operators VBA?

 VBA Operators :

An Operator can be defined using a simple expression - 4 + 5 is equal to 9. Here, 4 and 5 are called operands and + is called operator. VBA supports following types of operators −

• Arithmetic Operators
• Comparison Operators
• Logical (or Relational) Operators
• Concatenation Operators

The Arithmatic Operators : 

Following arithmetic operators are supported by VBA.

Assume variable A holds 5 and variable B holds 10, then −

http://www.tutorialspoint.com/

What is VBA - Constants?

VBA - Constants : 

Constant is a named memory location used to hold a value that CANNOT be changed during the script execution. If a user tries to change a Constant value, the script execution ends up with an error. Constants are declared the same way the variables are declared.

Following are the rules for naming a constant.

• You must use a letter as the first character.
• You can't use a space, period (.), exclamation mark (!), or the characters @, &, $, # in the name.
• Name can't exceed 255 characters in length.
• You cannot use Visual Basic reserved keywords as variable name.

Syntax

In VBA, we need to assign a value to the declared Constants. An error is thrown, if we try to change the value of the constant.

http://www.tutorialspoint.com/

What is VBA - Variables

Variable is a named memory location used to hold a value that can be changed during the script execution. Following are the basic rules for naming a variable.

• You must use a letter as the first character.
• You can't use a space, period (.), exclamation mark (!), or the characters @, &, $, # in the name.
• Name can't exceed 255 characters in length.
• You cannot use Visual Basic reserved keywords as variable name.

Syntax

In VBA, you need to declare the variables before using them.

Dim <<variable_name>> As <<variable_type>>

Data Types

There are many VBA data types, which can be divided into two main categories, namely numeric and non-numeric data types.

http://www.tutorialspoint.com/

What is Input Box VBA?

Input Box VBA :

The InputBox function prompts the users to enter values. After entering the values, if the user clicks the OK button or presses ENTER on the keyboard, the InputBox function will return the text in the text box. If the user clicks the Cancel button, the function will return an empty string ("").

Syntax

InputBox(prompt[,title][,default][,xpos][,ypos][,helpfile,context])

Parameter Description

• Prompt − A required parameter. A String that is displayed as a message in the dialog box. The maximum length of prompt is approximately 1024 characters. If the message extends to more than a line, then the lines can be separated using a carriage return character (Chr(13)) or a linefeed character (Chr(10)) between each line.

http://www.tutorialspoint.com/

What is Message Box VBA?

Message Box VBA : 

The MsgBox function displays a message box and waits for the user to click a button and then an action is performed based on the button clicked by the user.

Syntax

MsgBox(prompt[,buttons][,title][,helpfile,context])

Parameter Description

• Prompt − A Required Parameter. A String that is displayed as a message in the dialog box. The maximum length of prompt is approximately 1024 characters. If the message extends to more than a line, then the lines can be separated using a carriage return character (Chr(13)) or a linefeed character (Chr(10)) between each line.
• Buttons − An Optional Parameter. A Numeric expression that specifies the type of buttons to display, the icon style to use, the identity of the default button, and the modality of the message box. If left blank, the default value for buttons is 0.

for more courses visit here : http://www.tutorialspoint.com/

What is Macro Comments VBA?

Macro Comments VBA : 

Comments are used to document the program logic and the user information with which other programmers can seamlessly work on the same code in future.

It includes information such as developed by, modified by, and can also include incorporated logic. Comments are ignored by the interpreter while execution.

Comments in VBA are denoted by two methods.

• Any statement that starts with a Single Quote (') is treated as comment. Following is an example.

http://www.tutorialspoint.com/

What is Excel Terms?

Modules : 

Modules is the area where the code is written. This is a new Workbook, hence there aren't any Modules.

To insert a Module, navigate to Insert → Module. Once a module is inserted 'module1' is created.

Within the modules, we can write VBA code and the code is written within a Procedure. A Procedure/Sub Procedure is a series of VBA statements instructing what to do.

Procedure

Procedures are a group of statements executed as a whole, which instructs Excel how to perform a specific task. The task performed can be a very simple or a very complicated task. However, it is a good practice to break down complicated procedures into smaller ones.

Visit : http://www.tutorialspoint.com/

What is Excel Macros VBA?

 Excel Macros VBA : 

Step 1 − First, enable 'Developer' menu in Excel 20XX. To do the same, click File → Options.

Step 2 − Click ‘Customize the Ribbon’ tab and check 'Developer'. Click 'OK'.

Step 3 − The 'Developer' ribbon appears in the menu bar.

Step 4 − Click the 'Visual Basic' button to open the VBA Editor.

for more : http://www.tutorialspoint.com/

What is VBA Overview?

 VBA Overview : 

VBA stands for Visual Basic for Applications an event-driven programming language from Microsoft that is now predominantly used with Microsoft office applications such as MSExcel, MS-Word, and MS-Access.

It helps techies to build customized applications and solutions to enhance the capabilities of those applications. The advantage of this facility is that you NEED NOT have visual basic installed on our PC, however, installing Office will implicitly help in achieving the purpose.

for more visit : http://www.tutorialspoint.com/

What is VBA?

VBA :

VBA stands for Visual Basic for Applications, an event-driven programming language from Microsoft. It is now predominantly used with Microsoft Office applications such as MSExcel, MS-Word and MS-Access.

for more details visit: http://www.tutorialspoint.com/

What is Vim Installation And Configuration

Vim is lightweight package and its installation is really simple. In this chapter, we will discuss following items −

• Installation on Windows platform
• Installation on Debian based Linux
• Installation on RPM based Linux

Installation on Windows platform

Vim doesn’t have any specific requirements. It is simple software bundle which provides all dependencies.

Installation

• To download Vim visit vim.org
• Click on Download option from left pane
• Click on PC - MS-DOS and MS-Windows option
• Download .exe installer from this page. At the time of writing this tutorial installer name was gvim80.exe
• Double click on installer and follow on screen instructions to complete installation

What is the Introduction of Vim?

Vim editor is one of the more popular text editors we use today. It is a clone of the Vi editor and is written by Bram Moolenaar. It is cross platform editor and available on most popular platforms like Windows, Linux, Mac and other UNIX variants. In this chapter, we will discuss following items −

• Introduction
• Features of Vim
• Why Vim was created?

Introduction

Vim is acronym for Vi IMproved. It is free and open source text editor written by Bram Moolenaar. It was first released in 1991 for UNIX variants and its main goal was to provide enhancement to the Vi editor, which was released way back in 1976.

Vim is considered as clone Vi editor. Like Vi, it is also command centric editor. One of the advantage of learning Vim is – it is available everywhere. Take any UNIX variant like Linux, Mac, HP-UX, AIX and many more, Vim is there by default. Vim traditionally does not have GUI but now there is separate installer called gVim which provides GUI.

https://www.tutorialspoint.com/index.htm

What is Vim?

VIM proved (henceforth referred to as Vim) editor is one of the popular text editors. It is clone of Vi editor and written by Bram Moolenaar. It is cross platform editor and available on most popular platforms like Windows, Linux, Mac and other UNIX variants. It is command-centric editor, so beginners might find it difficult to work with it. But once you master it, you can solve many complex text-related tasks with few Vim commands. After completing this tutorial, readers should be able to use Vim fluently.

for more info visit : https://www.tutorialspoint.com/index.htm

What is Full Length Example of YAML?

The following full-length example specifies the construct of YAML which includes symbols and various representations which will be helpful while converting or processing them in JSON format. These attributes are also called as key names in JSON documents. These notations are created for security purposes.

The above YAML format represents various attributes of defaults, adapter, and host with various other attributes. YAML also keeps a log of every file generated which maintains a track of error messages generated. On converting the specified YAML file in JSON format we get a desired output

What is YAML - Scalars and Tags

Scalars in YAML are written in block format using a literal type which is denoted as(|). It denotes line breaks count. In YAML, scalars are written in folded style (>) where each line denotes a folded space which ends with an empty line or more indented line.

https://www.tutorialspoint.com/index.htm

What is YAML Collections and Structures ?

YAML includes block collections which use indentation for scope. Here, each entry begins with a new line. Block sequences in collections indicate each entry with a dash and space (-). In YAML, block collections styles are not denoted by any specific indicator. Block collection in YAML can distinguished from other scalar quantities with an identification of key value pair included in them.

Mappings are the representation of key value as included in JSON structure. It is used often in multi-lingual support systems and creation of API in mobile applications. Mappings use key value pair representation with the usage of colon and space (:)

https://www.tutorialspoint.com/yaml/yaml_collections_and_structures.htm

What is YAML Comments

Now that you are comfortable with the syntax and basics of YAML, let us proceed further into its details. In this chapter, we will see how to use comments in YAML.

YAML supports single line comments. Its structure is explained below with the help of an example −

for more info visit: https://www.tutorialspoint.com/yaml/yaml_comments.htm

What is Indentation and Separation in YAML?

Indentation of YAML

YAML does not include any mandatory spaces. Further, there is no need to be consistent. The valid YAML indentation is shown below −

a:
   b:
      - c
      -  d
      - e
f:
      "ghi"

• You should remember the following rules while working with indentation in YAML:Flow blocks must be intended with at least some spaces with surrounding current block level.
• Flow content of YAML spans multiple lines. The beginning of flow content begins with { or [.
• Block list items include same indentation as the surrounding block level because - is considered as a part of indentation.

https://www.tutorialspoint.com/index.htm

What is the Basic of YAML?

 Let us learn its basics with syntax and other operations. Remember that YAML includes a human readable structured format.

Rules for Creating YAML file

When you are creating a file in YAML, you should remember the following basic rules −

• YAML is case sensitive
• The files should have .yaml as the extension
• YAML does not allow the use of tabs while creating YAML files; spaces are allowed instead.

https://www.tutorialspoint.com/index.htm

What is Introduction about YAML?

YAML Ain't Markup Language is a data serialization language that matches user’s expectations about data. It designed to be human friendly and works perfectly with other programming languages. It is useful to manage data and includes Unicode printable characters. This chapter will give you an introduction to YAML and gives you an idea about its features.

Format

Consider the text shown below −

Quick brown fox jumped over the lazy dog.

The YAML text for this will be represented as shown below −

yaml.load(Quick brown fox jumped over the lazy dog.)
>>'Quick brown fox jumped over the lazy dog.'

Note that YAML takes the value in string format and represents the output as mentioned above.

https://www.tutorialspoint.com/index.htm

What is YAML?

YAML is the abbreviated form of “YAML Ain’t markup language” is a data serialization language which is designed to be human -friendly and works well with other programming languages for everyday tasks. 

https://www.tutorialspoint.com/index.htm

What is Microcontrollers 8051 Interrupts

Interrupts are the events that temporarily suspend the main program, pass the control to the external sources and execute their task. It then passes the control to the main program where it had left off.

8051 has 5 interrupt signals, i.e. INT0, TFO, INT1, TF1, RI/TI. Each interrupt can be enabled or disabled by setting bits of the IE register and the whole interrupt system can be disabled by clearing the EA bit of the same register.

IE (Interrupt Enable) Register

This register is responsible for enabling and disabling the interrupt. EA register is set to one for enabling interrupts and set to 0 for disabling the interrupts. Its bit sequence and their meanings are shown in the following figure.

https://www.tutorialspoint.com/index.htm

What is Microcontrollers 8051 Input Output Ports

8051 microcontrollers have 4 I/O ports each of 8-bit, which can be configured as input or output. Hence, total 32 input/output pins allow the microcontroller to be connected with the peripheral devices.

• Pin configuration, i.e. the pin can be configured as 1 for input and 0 for output as per the logic state.
  • Input/Output (I/O) pin − All the circuits within the microcontroller must be connected to one of its pins except P0 port because it does not have pull-up resistors built-in.
  • Input pin − Logic 1 is applied to a bit of the P register. The output FE transistor is turned off and the other pin remains connected to the power supply voltage over a pull-up resistor of high resistance.
• Port 0 − The P0 (zero) port is characterized by two functions −
  • When the external memory is used then the lower address byte (addresses A0A7) is applied on it, else all bits of this port are configured as input/output.
  • When P0 port is configured as an output then other ports consisting of pins with built-in pull-up resistor connected by its end to 5V power supply, the pins of this port have this resistor left out.

Input Configuration

If any pin of this port is configured as an input, then it acts as if it “floats”, i.e. the input has unlimited input resistance and in-determined potential.

Output Configuration

When the pin is configured as an output, then it acts as an “open drain”. By applying logic 0 to a port bit, the appropriate pin will be connected to ground (0V), and applying logic 1, the external output will keep on “floating”.

In order to apply logic 1 (5V) on this output pin, it is necessary to build an external pullup resistor.

Port 1

P1 is a true I/O port as it doesn’t have any alternative functions as in P0, but this port can be configured as general I/O only. It has a built-in pull-up resistor and is completely compatible with TTL circuits.

Port 2

P2 is similar to P0 when the external memory is used. Pins of this port occupy addresses intended for the external memory chip. This port can be used for higher address byte with addresses A8-A15. When no memory is added then this port can be used as a general input/output port similar to Port 1.

Port 3

In this port, functions are similar to other ports except that the logic 1 must be applied to appropriate bit of the P3 register.

https://www.tutorialspoint.com/index.htm

What is Microcontrollers 8051 Pin Description?

The pin diagram of 8051 microcontroller looks as follows −

• Pins 1 to 8 − These pins are known as Port 1. This port doesn’t serve any other functions. It is internally pulled up, bi-directional I/O port.
• Pin 9 − It is a RESET pin, which is used to reset the microcontroller to its initial values.
• Pins 10 to 17 − These pins are known as Port 3. This port serves some functions like interrupts, timer input, control signals, serial communication signals RxD and TxD, etc.

https://www.tutorialspoint.com/index.htm

What is Microcontrollers 8051 Architecture?

8051 microcontroller is designed by Intel in 1981. It is an 8-bit microcontroller. It is built with 40 pins DIP (dual inline package), 4kb of ROM storage and 128 bytes of RAM storage, 2 16-bit timers. It consists of are four parallel 8-bit ports, which are programmable as well as addressable as per the requirement. An on-chip crystal oscillator is integrated in the microcontroller having crystal frequency of 12 MHz.

Let us now discuss the architecture of 8051 Microcontroller.

In the following diagram, the system bus connects all the support devices to the CPU. The system bus consists of an 8-bit data bus, a 16-bit address bus and bus control signals. All other devices like program memory, ports, data memory, serial interface, interrupt control, timers, and the CPU are all interfaced together through the system bus.

https://www.tutorialspoint.com/index.htm

What is Microcontrollers?

A microcontroller is a small and low-cost microcomputer, which is designed to perform the specific tasks of embedded systems like displaying microwave’s information, receiving remote signals, etc.

The general microcontroller consists of the processor, the memory (RAM, ROM, EPROM), Serial ports, peripherals (timers, counters), etc.

Difference between Microprocessor and Microcontroller

The following table highlights the differences between a microprocessor and a microcontroller −

Microcontroller	Microprocessor
Microcontrollers are used to execute a single task within an application.	Microprocessors are used for big applications.
Its designing and hardware cost is low.	Its designing and hardware cost is high.
Easy to replace.	Not so easy to replace.
It is built with CMOS technology, which requires less power to operate.	Its power consumption is high because it has to control the entire system.
It consists of CPU, RAM, ROM, I/O ports.	It doesn’t consist of RAM, ROM, I/O ports. It uses its pins to interface to peripheral devices.

https://www.tutorialspoint.com/index.htm

What is Microprocessor - 8257 DMA Controller

DMA stands for Direct Memory Access. It is designed by Intel to transfer data at the fastest rate. It allows the device to transfer the data directly to/from memory without any interference of the CPU.

Using a DMA controller, the device requests the CPU to hold its data, address and control bus, so the device is free to transfer data directly to/from the memory. The DMA data transfer is initiated only after receiving HLDA signal from the CPU.

How DMA Operations are Performed?

Following is the sequence of operations performed by a DMA −

• Initially, when any device has to send data between the device and the memory, the device has to send DMA request (DRQ) to DMA controller.
• The DMA controller sends Hold request (HRQ) to the CPU and waits for the CPU to assert the HLDA.
• Then the microprocessor tri-states all the data bus, address bus, and control bus. The CPU leaves the control over bus and acknowledges the HOLD request through HLDA signal.
• Now the CPU is in HOLD state and the DMA controller has to manage the operations over buses between the CPU, memory, and I/O devices.

https://www.tutorialspoint.com/index.htm

8279 Programmable Keyboard

8279 programmable keyboard/display controller is designed by Intel that interfaces a keyboard with the CPU. The keyboard first scans the keyboard and identifies if any key has been pressed. It then sends their relative response of the pressed key to the CPU and vice-a-versa.

How Many Ways the Keyboard is Interfaced with the CPU?

The Keyboard can be interfaced either in the interrupt or the polled mode. In the Interrupt mode, the processor is requested service only if any key is pressed, otherwise the CPU will continue with its main task.

In the Polled mode, the CPU periodically reads an internal flag of 8279 to check whether any key is pressed or not with key pressure.

How Does 8279 Keyboard Work?

The keyboard consists of maximum 64 keys, which are interfaced with the CPU by using the key-codes. These key-codes are de-bounced and stored in an 8-byte FIFORAM, which can be accessed by the CPU. If more than 8 characters are entered in the FIFO, then it means more than eight keys are pressed at a time. This is when the overrun status is set.

If a FIFO contains a valid key entry, then the CPU is interrupted in an interrupt mode else the CPU checks the status in polling to read the entry. Once the CPU reads a key entry, then FIFO is updated, and the key entry is pushed out of the FIFO to generate space for new entries.

See more info visit : https://www.tutorialspoint.com/index.htm